Given the odds of getting an unlockable 6950, I would say just get a 6970.
Yeah that's why the question came up. I was lucky to get one card that unlocked.
If adding one 6970 is going to give the same performance as two in xfire, I have another option than taking a chance at another unlock.
If it matters, I just unlocked the shaders on the 6950; didn't flash a 6970 bios to it.
What stability issues would you think may come up?