Aside from the small hiccups I've gotten whilst crossfired, it was definitely one of the best decisions to do so.
I never dip below 90FPS in BC2 maxed out with 8xaa, and it can get as high as 130. Who can complain?
It was really eye-opening for me to see no lower than 60fps in 3dmark vantage. I don't think I ever ran it with my 6950 on it's own, only with a 6870. It probably averaged in the ~100fps range, and lowest it ever got was about 65fps or so on all tests except physics. BFBC2 at 1920x1080 resolution I never really noticed low framerates since I went sandybridge replacing LGA775. I can't wait to move to my final destination to give eyefinity a go on watercooled overclocked and unlocked 6950 2gbs.