It really depends. The hotfixes are going to help, or at least not hurt. I know there were some fixes out for the Crysis issues, which I think are covered in that link I sent you. A quick google search on it might help. I don't have Crysis, so I don't know much about what to tell you. This thread might provide some insight to you, though it looks like Crysis is still having multi-GPU issues: AMD Game Forums - Crossfire boosted in Crysis patch 1.1 DX10.
As for performance, like I said, it depends. Some of it comes down to how good the coding for the program was. Also, it will depend on how good the Crossfire profile is. You should get better performance, but there are certainly times where it doesn't give better performance (though it won't often get worse, unless the coding is terrible).
Watch for Catalyst 8.1. Should be out by the end of this week, I'd guess. Maybe beginning of next week. Either way, it'll be that much more important for you to keep the drivers updated now that you have Crossfire (I'd recommend staying away from betas, though).
