i've heard that some games have their own physics , so counting 560's Physx to pro's group as full would be mistake, but also you forgot that the 560 has higher power consumption
PhysX is a feature found on some games that can basically only be run on Nvidia cards. You can't do it on AMD cards. Power consumption is overrated, as the difference in power amounts to basically a nominal difference in the cost of your power bill.
Anyway, it's already been shown that a good GTX 560 is better on BFBC2 at the specified resolution than the 6950 and produces higher minimum FPS than even the 6970.