Vsync solves screen tearing, because screen tearing occurs whenever the FPS goes above the refresh rate of the screen. But whenever the FPS drops below the refresh rate of the screen while using normal vsync the FPS will lock at a much lower FPS.
Example: 60 HZ screen. FPS drops below 60 during an intensive fight. Then the FPS will lock in at 30, even though actual FPS might be at 58 and when it drops below 30, then it will lock in at 15, again even though the actual FPS might be at 25.
Just listen to Linus, if you don't trust me.
http://www.youtube.com/watch?v=DAiPmazmR_M - Adaptive vsync explanation.
PhysX is in more than 20 games
http://www.geforce.co.uk/hardware/technology/PhysX/pc-games
TXAA is in more than 2 games
Assassins Creed 3, Batman: Arkham City, Crysis 3, The Secret World and I'm positive there is a few more.
Crysis 3 is out, there is an open BETA and AMD GPUs simply isn't optimized for the game. CF isn't even supported yet, even though it's running on a well known engine.
You didn't say anything about "75% performance of GTX 670 SLI", you said Radeon 7970 Ghz ed. was almost close to beat them.
You didn't measure anything. If you look at the benchmarks then they don't support your statement.
http://www.anandtech.com/show/6025/radeon-hd-7970-ghz-edition-review-catching-up-to-gtx-680/16 - 7970 Ghz ed. power consumption.