Where R600 will fail is upcoming DX10 games with that "the way it's meant to be played logo", that's one thing I'm willing to bet on. Crysis, World In Conflict, QuakeWars are all nVidia's friends.
It would have to be a real monster of a card to beat nVidia in these titles.
Just because its stamped with the green machines logo doesnt mean ATi automatically has a performance pitfall, many popular games have shown this, some even have driver bugs for months on nVidia hardware (terrible bugs such has what EQ2 experianced for months after launch as the recent problems with TR:Legend) while ATi hardware functions pretty much without issue.
And contrary to popular belief ATi does get into the Devs houses, its just not in your face. Prey for example, was backed by ATi, and i bet most people didnt even notice.
Crytek, by the way, has their hand in multiple pockets. If you'll remember Farcry, even while being backed by nVidia, was one of the first games to make use of SM2.0b and they also created that machinima project for ATI, AND that game remained one of ATi's strengths for benchmarking up until the current 8800 launch.
Brand stamping on games has ment relatively little since its introduction in terms of the performance outcome.
And i dont know about the rest of you, but i'd prefer my hardware just work and not see its brand logo popup during the loading of a game, rather then have it fail or faulter and get the logo. Doesnt mean anything to me if it works right (which it should anyway so i expect it) and if doesnt its an embarrassment.
Lastly i dont see where they have room to optimize game code for one peice of hardware over the other when it comes to DX10+ since it should be almost completely hardware agnostic unlike previous DirectX versions. OpenGL is another story.