The issue with all these third party programs that window the game and allow you to run the game in a pseudo full screen mode is that you still lose performance in windowed vs true full screen.

It's a pretty big hit, maybe you don't notice it if you're playing in a lower setting or your PC is really beefy but I have a fairly decent PC and I have to lower my settings considerably if I want to play the game in windowed mode and still get worse average FPS.

I personally would like to see resolution to this at some point in the future.