Why would you say that Nvidia is notorious for OCing poorly? The Fermis on average OC much better than Caymans. My 460s for example start at 675 and OCs to 950 with 1.165V. 580s start at 772. The 6900's memory does OC extremely well but that only gives 2-3fps difference so it's the core that most are more concerned with. Going from 880-1000 isn't as impressive as 772-950 or above.
I am just going to wait as I have been to see what it does but on paper it isn't looking good.