Did I make the right choice? (NAS + HDD)

[aisback]

Hello everyone, I was planning on doing a full build originally but due to personal reasons that would take too long. So I have decided to go down the Synology route, I intially got the 923+ but since it didn’t support Quick sync I decided to send it back. 
 

Unfortunately the only option from them appears to be a 423+ which has an older Intel CPU and half of the ram soldered so I can only add one more RAM module.  For my current needs this will do. It'll be mostly for a plex server and some data backup so nothing too intensive. I've also heard the software is pretty good.  
 

The drives is why I'm making this post as it appears I might have gotten an amazing deal. I have managed to get 4x 6TB Toshiba MG08ADA600E (sold as new). These appear to be enterprise HDDs and only cost me just over £300 for all of them in total. Has anyone had any experience with these drives?

 

I do have plex pass so I know the streaming will be fine die to hardware acceleration. 

 

I also can't see the drives being on a compatibility list so it does make me nervous especially since the whole WD RED issue.