According to that, the 760 averages anywhere from 5 to 15% faster, which fits seeing that it's just over 10% more expensive.
Aside from Battlefield, Bioshock, and Crysis 3, they are essentially equal. You're not going to notice the 2-3 FPS difference in other games. If you're a serious enthusiast for those games, it might be worth it, but otherwise not.
And why is it irrelevant? If I had a Shield and wanted to use it's streaming capabilities, $25 isn't much of a price to pay, especially considering that I already spent $250 on what would be a wasted device if I didn't have Nvidia's streaming capabilities.
If he's using the streaming capabilities, I suppose. It seems pretty useless IMO, but whatever.