Yes, the pcper articles included interviews with AMD; they made no attempt to finger-point or deny the problem, but got right on it. I'm not running multiple cards though. I've used cards from both companies, and have little preference. When I was playing Sacred 2 I wanted the PhysX, and now that I'm mining (probably for another couple months) I use AMD; in fact my HD7970 has yet to play a game, but it's been running at 96%+ since it arrived a little more than a week ago.
Anyway, we're wandering a little too OT here. On pure gaming performance, there may be little to recommend one of these cards over the other, but factors like free games and PhysX/mining could really skew their relative value.