Well, let me get in here before all the Y-comp bashing gets going...
I owned an AK shorty, I currently own an M4 with mini-Y. Both did the job wonderfully. However, there is definitely a difference in shooting the two.
The AK controls muzzle flip beautifully, you are pretty much right on target after pulling the trigger. However, it is pretty loud and throws a lot of blast out to your sides.
The mini-Y comp is also excellent at keeping the muzzle flat. However, it throws a lot of the 'shockwave' right back in your face. It feels like a short little 'poof' of air when you fire and it can be startling if you're not expecting it. In my experience, it does just a little better job at keeping you on target after firing a round. I love my mini-Y and have long gotten over the side effects. (I have actually grown to like it and hardly even notice it anymore)
I would say try and shoot them both before you buy if you can. I hope my experience helps!