That doesn't make any sense.
If you change the bios to 6950 then install updated drivers wouldn't it be the drivers for 6950?
And then you switch back to the bios for 6970 and use the installed drivers for 6950?
What about future driver updates!?!
Even if AMD decides not to do some sort of a fix in future drivers there are no guaranties that the correct drivers will be installed, or am I wrong?