I noticed  while looking for 2900 pros (since I'm probably going to buy one myself) that on Overclockers.co.uk they seemed to have a 2900 pro for the same price as an xt, (1st thought, wtf? ) but looking closer I noticed it was gddr4 and with 1024 mb of vram, while the xt was only gddr3, so I'm wondering, which would perform better?
oh, and btw the main point is the gddr4 not the 1024 mb (since that probably means jack)

I remember seeing how the 2900XT 1GB GDDR4 didn't do that much good over the 2900XT 512 GDDR3, so I'm guessing BASED on those results (Since both the Pro and XT are pretty much the same except for clocks) that you might find maybe a 5% increase in performance in the 1GB GDDR4 Pro depending on the clocks over the 512 GDDR3 Pro. (Meaning the XT would most likely be faster because of the clocks)

that seems pretty well reasoned, but I wonder if you get better performance out of an OC'd gddr4 pro than an OC'd gddr3 xt??

The orginal XT with GDDR2 had problems.    I hope this is fixed, as well as giving the 2900 series enough texture fill. (it already has 320 streams)  Then the 2900 series should be a screamer.

Depends on how far the GPU can go... Remember that the Pro GPU is supposed to be a "failed" XT GPU. But I for one don't think that one the GDDR4 is actually worth it at $50-60 more the price of the 512 Pro, if you're willing to spend $330-340 on a graphics card, then spend a bit more and go with a 2900XT with a GPU that passed whatever quality tests they undergo. At least that's the way I see it.

I was under the impresion that the latencies in the Gddr4 didnt really have that much of an improvement over the Gddr3.
My thinking is that this is a marketing ploy and i dont think it is worth it,what price for a Gddr3 512 Pro compared to a Gddr3 512 XT would be what i would be looking at.Taking into account that we are assuming that the Pro will OC a bit to get somewhere near a stock XT if you are lucky.
The other thing to ask yourself is are you running resolutions where you are going to use 1024? as you say it dont really mean much.
Cant really see the performance being worth the extra cash myself.
Just my opinion though    
  Mactronix

Wasted memory.