I'm running the Windows 10 Technical Preview on a 2013 MacBook Air, solely for gaming. So far I've only played Halflife 2, and it's much better than under OSX. I had to force it to run windowed, rather than true full screen, because full screen had some issues. I don't notice the tiny window bar once I've started playing.

The Technical Preview is free and easy to setup with Bootcamp, so you may as well give it a shot.