The ultimate benefit of extra vram which holds no debate at all is:
If it's needed it's available! If you don't have it... unlucky, scaling back is your only option!
You don't think it's needed, I do, we simply have a difference of opinion.
I would also point out that
the 570/6970 trade blows more often than not, it depends who puts their sticker on the tin-You are looking like you only have green tinted glasses kissenger.
At this moment in time it's pure speculation whether the 448 is a disabled or ever so slightly broken 570, so it's not a given that
any will unlock, if there is no dual bios switch(I haven't seen any on the pics) then god help us here at the forum with the 'Help I bricked my 560 ti 448 while flashing the bios' threads.
The shake up will maybe come on Tuesday if it's a 100% hard launch with the 448, it is looking likely though.
Amd may slash prices as the 6950/70's are going to be eol soon anyway if they are not already and maybe also in reply to Nvidia's slashing of the 1Gb 560's prices too.
There is also a possibilty the 7870 is going to be even faster than a 6970 as well, so they won't have an option but drop current gpu's when the 7870 is released.
There is also a very slim chance that Amd were to do what Nvidia did with the 580 last year and throw the 7870 out at the same time as the 448 just to burst their bubble.
I doubt they will pull one over on Nvidia with a sneaky release, but you never know.