However, even in our small sampling we have people who are reporting it didn't work 100%.
IE:
I'm absolutely not saying don't do it, I'm just saying that you may not get what you want if you go that route. We all know of cpu's that overclock amazingly well, but we also know no overclock is guaranteed. Every bit of silicone is different.
If you feel the chance of getting a 6950 that is unlockable is very good, go for it. I might pick up a 6950 and flash it instead of buying another 6970, but right now the sample size is a bit small. I've been searching and haven't found more than 100 people that are saying success. It's just a bit small of a sample size to really give us the full picture right now.
If it works on almost every card besides a bad apple, I certainly will be on the 6950 flashed to 6970 band-wagon, but I won't be sending my 6970 back, especially since I just ordered a full cover block for it today!