I'm not going to correct you on that, it's obvious that some games can make a use of a higher memory buffer but that doesn't mean it's necessary or useful at all for an average user (gaming at 1080p or lower).
You probably misunderstood my post judging by the second paragraph. Radeon 6950s are brilliant cards, not all of them can unlock the shaders though and 1GB ones certainly can't (and that's what I mentioned earlier). There's some memory issues that won't allow some cards reach stock 6970's clocks but it doesn't affect performance by much (5% at most) and the cores overclock generally the same as 6970s (which is some 10% over stock 6970s but you have to take noise of the cooler and temps into account).
GeForce GTX 560 TI would be my choice simply because:
a) it's cheaper
b) it overclocks bloody well
c) I'd fancy a change
I'm not moving to Nvidia camp any time soon though.
That's not my point of view, it is what reviews confirm and what many users report. I appreciate you take a different stand on that matter though.