I think the test made by DailyTech is not a solid test. Did you wonder why the X2900XTX have the same or a little less performance than the X2900XT (where it should be less powerfull than a XTX version) ?
They didn't compare the image quality between a 8800 GTS/GTX with those X2900 XT/XTX, but just only pure performance. I recently have a 8800 GTX, it does his job perfectly except ONE thing, and this is about how the image/texture is rendered, I mean the filtering parts. When I played GTR 2 with my old ATI 9800 Pro, the road were kicking ass. But when I receive my 8800 GTX, roads looks like crap. I'm not an ATI fanboy, but I'm just a little desappointed with nVidia. It's been a while they don't fix these filtering quality. (I don't know the right word in english) but the quality related with textures are crap in certain case and it's a little annoying when you taste the same game with an ATI card.
I think, X2900 XTX can do better performance. So, I will wait for further more test from other technical reviewer like guru3D, anandtech, tom'shardware, or hardware.fr.