The performance seemed to be the same with SLI disabled/enabled. The driver version I'm currently using is 163.75 (released yesterday).
Also, I guess I'm not the only one experiencing these issues:
http://gearsforums.epicgames.com/showthread.php?t=583230
Of course it wouldn't hurt to try, and it would probably even run great. But what's the point of buying a very high-end gaming PC and I can't even play GOW on it's highest available settings?
I read the article, it was very well written and thorough. I am indeed going for the 4x AA, and I'm...