Not personally a fan of instant replay for pool. I don't mind so much with other sports, where the other guy's actions and other things not under you control might be significant, but you're generally in complete control when you're shooting pool. With some rare exceptions where you're really snookered and the only possible legal shot forces you to come very close to fouling, if you end up shooting in a way that flirts with a foul, it's you're own fault. Along with that, I think refs should generally err on the side of calling the foul if it's so close that you can really go either way.
I just don't think we need anything else to slow down and interrupt the flow of the game. I'm not a 15 second shot clock guy, but I also don't want to see it turn into yet another head buried in the cell phone activity.
Just my opinion.