9.5mm is definitely fine for M6 since none of the forces on this small machine will get anywhere near the rating of an M6 bolt. I'd advise using threadlock to make sure any bolts don't vibrate loose.

Quote Originally Posted by WandrinAndy View Post
- RM1610 ballscrews on X,Y,Z
Good choice for X and Y but there's no need to use 10mm pitch on the Z-axis. Keep the resolution by using RM1605 on Z.