I'm on Linux Mint right now. It's been working really well.
Basically no lag at all with the proprietary drivers, one thing however is driving me insane.
At the lower end of the screen (when I play WoW) i'm getting a lot of screen tearing.
It's looking really ugly when I move my character around.
Not sure what could cause this tbh. Gonna see if It gets better using some other drivers.
edit: I managed to find that it's caused by the vsync, so I disabled it.
Now I got a lot more lagg instead...