My brother is also looking for a new mouse for D3. However the Naga seems to have a lot of buttons on it (mostly for WoW I guess), so that was a bit of a turn off for him. The D3 mouse is cool, but you can hardly reach the buttons on the right side of the mouse (if you are right-handed).
He's probably going for the new MX518 from Logitech (the G400 it's called).
I have the old MX518 and it works perfect, no issues whatsoever and used it with WoW a lot. Though it has only 2 extra buttons on the side so you still need the keyboard..
Yep, you can rebind all the buttons. I've left it at DPI increase/decrease for BF3.
I currently use a Logitech G500, been going strong for 2 years now. I have 0 complaints.