Ok, this is good news for now but I think we all need to realize something. DX10 is
new! We've been riding the DX9 bandwagon for so long we completely maxed out it's ability as seen in Crysis. The DX9 version compared to the DX10 version is slightly different, but nowhere devastating enough to force someone to use DX10. With all of this in mind, future games more than likely won't do the same thing. As DX10 becomes more utilized and refined, we'll start to see more and more of a performance gap between DX9 and DX10 (in DX10's favor obviously).
Maybe the best analogy for you guys (since every other thread is about building a pc) is the difference between single and dual/quad cores for gaming. Not a big difference because it wasn't utilized back when multicores hit the market. Well now is coming the time when multiple cores can be utilized in games and are now outperforming the single cores. Single cores = DX9 ; Multi-cores = DX10. That could be horrible but it made sense to me when it popped in my head a minute ago
I could be way off but that seems to be the track record of all the DX series from what I remember.