I'm running dual 5830s on my test machine clocked at 875,900.  Also using the latest ubuntu 11.04 x64, sdk 2.4 and catalyst 11.6.

using Deepbit pool, hashkill is delivering about 433Mhash/sec but phoenix 1.5/phatk is delivering about 528Mhash/sec.  Should I be using an earlier driver?  I tried playing with -D, -G1, -G2, -G3, -G4.  Is there anything else I can try to duplicate the results other folks have had?