Just my $0.02.
If you want the performance of an HD 6970, purchase an HD 6970, unless you're willing to eat the cost of a bricked card.
Purchasing an HD6950 and expecting to unlock it to an HD 6970 is fool-hardy at best and borderline (if not out-right) illegal if the flash fails and you attempt to return it as faulty.
Again, just my two cents.
-Wolf sends