This Doom3 benchmark article at Hardocp might be interesting to read given the context of this post. It shows the FX5600 Ultra consistently out-performing the 9600 Pro. In fact, if I remember the article correctly, they state that all FX cards, even the lowly 5200, do well using this new engine.
I don't know much about video card tech issues, but I have a feeling that the Doom3 engine is going to redefine things, and that the FX cards will do quite well. Right now, I'm wondering that if ATI cannot improve performance via their drivers then they may suddenly find themselves playing catchup big time (which might mean premature obsolescene for many of their current card owners!).
I have both an ATI 9600 Pro and a TI4200 and I like them both very much. Currently I'm leaning toward the eVGA 5600 Ultra, partly because of
this review. The card they have shipped with 2.2ns RAM (rated to do 900MHz) and they tested the card at 485/979. They only give it an 80%, but then they didn't have the Doom3 tool that hardocp has.