"2 x Radeon HD 6950 1 GB in CrossFire"
"Excellent 2560x1600 performance"
I beg to differ. At $500+ users are looking for insane AA levels@25x16 or multimonitor setups. In both of these scenarios the 6950 fails to be "excellent":
http://www.hardocp.com/article/2011/02/24/amd_radeon_hd_6950_1gb_performance_review/
"In Battlefield: Bad Company 2 ...In the case of the AMD Radeon HD 6950 2GB video card, we were able to play this game with Transparency Antialiasing enabled at 4X AA. The 1GB Radeon HD 6950 1GB video card struggled when we enabled Transparency Antialiasing at 8X and 4X AA."
"Running Civilization V at 8X MSAA at 2560x1600 exposed the memory limitations on the 1GB Radeon HD 6950. For almost the first entire minute of gameplay performance dropped to a few frames per second until the frame buffer could catch up and texture everything out correctly. At that point performance was still erratic and choppy and overall slower than the 2GB Radeon HD 6950."
"F1 2010...When we tried to run this game at 8X MSAA on the 1GB Radeon HD 6950 and 1GB GeForce GTX 560 Ti we experience framerates in the 0-3 FPS range, which rendered playing the game impossible. However, the 2GB Radeon HD 6950 was completely playable at 8X MSAA!"
"In Metro 2033 we could not enable 4X MSAA at 2560x1600 on the two 1GB video cards in this game. Similar to the game above, this game was also unplayable with that enabled at this resolution. The 2GB Radeon HD 6950 was not playable with 4X AA enabled, but it was possible to do a run-through at least, it just had slow framerates, but it wasn’t near as low as the two 1GB video cards."
These are strong points to consider before rating the 1GB 6950CF an excellent rating at 2560x1600. Factoring in that these cards can not be unlock to 6970, and the 2GB 6950 becomes even more attractive at 25x16 and higher resolutions.
I believe that the 580 stands alone at the $500 price point, but Price x Performance wise there is little reason not to stretch the budget to 2GB 6950 in CF.
I better plan is to get a single 2Gb 6950, unlock it, see if it meets the games needs and add a secod card later.