I'm just back from a two day Tac Rifle class and I took my Shorty AK. It functioned perfectly, never a problem through two days of 800 rounds, dirt, dust, tall grass, sweat, fire ants, you name it.
I've read people complaining that it's loud, but I like the AK brake a lot; never noticed that it was any louder than no brake or a flash hider. It helped minimize what little muzzle rise there was. And, loud doesn't matter when you're using it to save your @ss.