Ah okay. Sounds like the same symptoms though. Crossfire - check. BC2 - check. High frame rates but laggy - check. Have you tried running just one monitor and seeing if there's any difference?
When i read that thread it made me try it with one monitor and i want to say it seemed very smooth, i just dont know if it was the server being really good and maybe it not being fully packed im going to test some more that tonight and see. I hope thats not the problem as i am very accustomed to my dual monitors.
I wish i had a group test to test with me and we could compare results.
The biggest difference for me was removing negative mouse accelaration. It might not hurt to give that a shot (there's an ea forum link on the net on how to do it). After applying the tweak, the game was completely different, so very smooth.