I do wonder how would the 2900 Have preformed if dx10 would have been left as it was going to be in the first place as the 3*** did seam get a boost. but is meant to be buggy code and to be honest if i had a 3*** and it worked ok i think i wouldn't care if i was getting a big incease in frames.
I've seen this tested somewhere. The 2900XT got no AA boost in AC. That's what you'd expect as the 2900XT is DX10.0.