The 7900 XT remains theoretically much more powerful.
On some games, the difference is minimal and there are 1-2 games where the 6950 XT is sometimes “better” (opti bug) but the 7900 XT consumes less, has 4GB more vram and continues to be optimized .
On the other hand we also see that on a lot of games, there can be a big diff.
Personally I have already noticed up to 40% more performance on the 7900 XT even if the average is ~15%.
6950 XT at 719€ is still a good price, considering the price of other GPUs.