I think it is reasonable to expect that full time refs would do a better job than part time refs. They will still make mistakes because, well, they are human. But they will likely make fewer mistakes and the mistakes may be less obvious/egregious.
Put replay on PI calls, and take away the stupid "catch with a football move" nonsense. It used to be it was a catch if you had control of the ball and both feet touched the ground. Now they're micro-analyzing any movement of the ball well after and if it touched the ground legally or not. If they want to speed up the game and keep a human element to it stop complicating something as simple as a catch.