Every new version up to 07~ was faster than previous on both of my rigs. 11~ version however is faster for single 5850, but on 5870+5850 rig Im noticing minor slowdown (due to bigger deltas, means best performance is same, but it can go little lower). In adition primary GPU set '-f0' stopped to bottleneck other GPU (but changing from -f35 to -f0 didnt add any speed). After all tests I've changed version on single gpu rig and left old one on double gpu rig.