MenSuRx

65% keyboards are just a smaller layout keyboard, it doesn't include some keys as the function key row, or the numpad, but it will still have the arrow keys. 65% keyboard tend to have around 66 keys. They are just in a more compact form, which some like me might really like how they look, but its mostly for the reason to save desk space.
The difference between Cherry MX and Outemu and Gaote are the manufacturers. Cherry MX are German made and are the original manufacturers of the first "gaming"/mechanical keyboard. When the patent ran out for the switches, other companies (nearly all from China) started to manufacture these mechanical keys. They are made nearly identical to each other with the exception that Cherry would most likely use higher quality materials to build the switches than the Chinese companies. Also the tolerance level (the consistency) of the switches would be higher in Cherry switches. But to be honest, performance wise, I haven't heard many complaints and for the lower price of the keyboards for non-cherry switches, its a good thing. Now some people can afford mechanical keyboards for a much lower price now.
I don't know about Gaote much, but i've read some complaints of the keyboards that use Gaote switches. Outemu seems fine. Feeling wise, theres little difference, Cherry MX feels better to type on than Outemu or Gaote switches but Outemu are more clickier but experience will vary. For people like me who have used Cherry all the way from the beginning, I personally just prefer Cherry switches because I can indeed tell the difference in typing experience, but its doesn't differ that much. I still do have non-cherry switches like the Tesoro Gram Spectrum and its not like i hate them. For the price, non-cherry switches can be a good thing.
 

65% keyboards are just a smaller layout keyboard, it doesn't include some keys as the function key row, or the numpad, but it will still have the arrow keys. 65% keyboard tend to have around 66 keys. They are just in a more compact form, which some like me might really like how they look, but its mostly for the reason to save desk space.
The difference between Cherry MX and Outemu and Gaote are the manufacturers. Cherry MX are German made and are the original manufacturers of the first "gaming"/mechanical keyboard. When the patent ran out for the switches, other companies (nearly all from China) started to manufacture these mechanical keys. They are made nearly identical to each other with the exception that Cherry would most likely use higher quality materials to build the switches than the Chinese companies. Also the tolerance level (the consistency) of the switches would be higher in Cherry switches. But to be honest, performance wise, I haven't heard many complaints and for the lower price of the keyboards for non-cherry switches, its a good thing. Now some people can afford mechanical keyboards for a much lower price now.
I don't know about Gaote much, but i've read some complaints of the keyboards that use Gaote switches. Outemu seems fine. Feeling wise, theres little difference, Cherry MX feels better to type on than Outemu or Gaote switches but Outemu are more clickier but experience will vary. For people like me who have used Cherry all the way from the beginning, I personally just prefer Cherry switches because I can indeed tell the difference in typing experience, but its doesn't differ that much. I still do have non-cherry switches like the Tesoro Gram Spectrum and its not like i hate them. For the price, non-cherry switches can be a good thing.
 

Yes they are, the 3366 is just Logitech's exclusive name, where Logitech might or might have not made some changes. The 3360 is just the public name for the Logitech exclusive 3366. The only difference which i'm not 100% sure is the dpi steps of 50 and 100 respectively.

This is the M65 Pro, it has the same sensor as the G303. It has the 3360 optical sensor...

Yes they are, the 3366 is just Logitech's exclusive name, where Logitech might or might have not made some changes. The 3360 is just the public name for the Logitech exclusive 3366. The only difference which i'm not 100% sure is the dpi steps of 50 and 100 respectively.

Yes they are, the 3366 is just Logitech's exclusive name, where Logitech might or might have not made some changes. The 3360 is just the public name for the Logitech exclusive 3366. The only difference which i'm not 100% sure is the dpi steps of 50 and 100 respectively.

Yes they are, the 3366 is just Logitech's exclusive name, where Logitech might or might have not made some changes. The 3360 is just the public name for the Logitech exclusive 3366. The only difference which i'm not 100% sure is the dpi steps of 50 and 100 respectively.

The main downsides of this mouse are its weight - 120g without the weights and the badly placed sniper button that can lead to accidental presses. These are pretty much deal breakers for most people.

This is the M65 Pro, it has the same sensor as the G303. It has the 3360 optical sensor...

They are basically the same sensor

I would also like to apologize for getting a little heated  
Oh well have a nice day  

Okay, lets just stick with that, and thats your opinion. I'm 100% fine on that. Since this argument is getting heated up, i have gone and re-edited some of my choice of words there and i would like to apologize. Your opinion is yours and my opinion is mine.

Logitech probably has the highest quality mice on the market, I don't see Steelseries making a mouse that feels higher quality than Logitech's G900, G602, G502, G402, I don't see one from Zowie, the only company that makes similar if not higher quality is Corsair with their aluminium body in the M65. Logitech has massively improved their products ever since their new G gaming and "Science wins" motto.  Their build quality is solid the materials used are solid. They use the best sensor available in the world. The only thing from Logitech's lineup that is sort of "cheap" is the G302/G303. However, i still use it to play CSGO. I agree that lighter mouse means better usage in FPS games, i agree but Logitech is nowhere near "mediocre". They make the most solid mouse. They have excellent customer support (guess what you would expect from the biggest company out of all the other competitors). Yes there are some other mouse better for FPS, Finalmouse makes better FPS mouse than Logitech but their build quality is sub-par. Zowie's are great but again their quality is similar to the G303. I would also say G303 is my preferred option over my Zowie EC2-A to use to play CSGO at GE level just because of that really nice 3366 sensor.
Also please don't spout nonsense if you don't know anything, Logitech's headsets are fine, their choice of earcups and comfortability may be an arguable but like other "gaming" headsets their audio quality is perfectly fine. Also Logitech does not use Kaihl switches, and they never had. They used Cherry MX switches then moved onto Romer-G switches which are manufactured by Omron, in terms of quality check, i would say Omron's are above Cherry, the feeling is debatable though. They also now have Cherry MX switches available as well. Also if you don't know, Logitech's speakers are really good value, sure their top models can't compete with other very high end audiophile companies but for value they are very good.

Whoa, I arrived to the party a bit late.
The G402 is just a bit over 100 grams and has a very good optical sensor that's impossible to spin out under normal use conditions, because of the added gyro. The weight might not be perfectly balanced, but most people don't notice that with light mice. The sensor is less smoothed than the glorified PWM3310 (used by many brands, including this forum's favourite - Zowie), thus it's a very popular mouse for competitive FPS. The only things that might not appeal to some people are the extra buttons and the shape.
 
The statement that Logitech gaming mice are "cancer" and mediocre is completely ridiculous since they are the ones pushing the industry forward and usually have technically flawless products. And no, the G402 doesn't have a sensor rattle, that's the G303 and the issue has been already resolved.

Logitech is considered a very good brand, I have no idea where you get this opinion from, but Logitech products are far, far from mediocre, and I'm sure many, many people would agree with me.

I have never used the CM Storm Devastator mouse but i'm pretty confident it will be perfectly fine. They are using Omron switches, i don't know how light your mouse switches are but the buttons are perfectly fine, if anything, they will probably be on the lighter side, but not as light as the razer deathadder 2013. They will also probably feel much better than your current mouse and it is a definitely good upgrade

The Rival 300 is a nice mice, but it is absolutely massive, i cannot use it with my 18cm hands. As you have mentioned above, some G303 do have sensor rattle issues, most cases they do then not. While some say Logitech has fixed this issue with their new batches, Logitech never publicly announced that they have. My G303 has a slight rattling sensor but its tracking is 100% accurate with no issues at all. G303's may have rattle but it varies with some rattling more than others, but while they do rattle, most of them don't have an issue with tracking or performance. I just used my Zowie EC2-A to play CSGO for the past 4 days, and today i went back to my G303 and i immediately noticed how much better i played with it. Also majority of the G502 won't have issues with the buttons wearing down. There may be some but of course all the G502's cant be made perfectly. I would say there would be less chance of G502's button producing double click issues than the Steelseries buttons or Zowie.
G303 is my favourite mice, due to it being light and small so i can aim better, also helped by its amazing sensor, its the most accurate and best sensor in the world for me. It beats the 3988 imo. 

Best option would be to get audiophile headphone and a microphone. However, if you cannot be bothered, then for a gaming headset, there is only 1 option. Hyper X Cloud 1/2. They are pretty much the only option for a gaming headset. Their sound quality is the best, its super comfortable and high quality (of course this is against the other gaming headset). Razer Kraken is no where as good as these, the only headset that comes close to being as good as these are the Steelseries Siberia V2.

Zowie mice, are just made for pure sensor performance. While the build quality is good, its not the best, it certainly doesn't come close to feeling the "best" and there are no other functions, such as RGB lighting etc. But then again, it was made for competitive esports, for pros, like finalmouse. Personally i like finalmouse tournament pro, its extremely good, like zowie, its on the fly, no gimmick just plastic shell and a high end performance sensor. While build quality depends on the unit that you receive, generally its not as good as zowie. BUT the performance of the finalmouse is a lot better.
 
Unless i'm playing CSGO competitively, i generally tend to not use my Zowie EC2-A or Finalmouse Tournament Pro, and i use my mionix castor or g502.