They're better than the EC2-A or EC1-A thumb buttons, which are the only right handed mice from Zowie.
This still looks like the best mouse from Logitech despite the side buttons, the weight and shape are great.
I really don't think Logitech has a better choice, I dislike the shape of the G303 and know the Pro G wouldn't be as comfortable to hold, even though it has better thumb buttons.
Not really interested in anything from Razer or Steel Series, or the FinalMouse stuff.
What is like the G403 but with good side buttons without anything else being worse? I honestly don't think there's much if anything.