I am running 13.04. AMD RV710. Dual 1900x1200. I installed on a single display and when I added the new one I got a lot of oddities. One is that one reboot sometimes I just don't get a window manager. It sometimes crashes as well.
Been very happy up to this point but I am running VM's in virutalbox and this is a work machine so I might have to go another route if this doesn't get figured out.