there's also a matter of drivers. the 10% lead in performance could just melt away if AMD decide to do some big driver update on the same day or within a week of kepler release to keep the 7970 competitive (I know it's unlikely, but still possible). as it stands, the green team fans who's been holding out for kepler will definately go for it, but those of us who got sick of waiting and went for a 7970 or even 7950 will probably be willing to just sit on our tahiti cards and wait for AMD to fix their drivers. in the end, this late release will cost Nvidia some sales in my opinion