Device is less than usefull. The only purpose I see to it is to prevent blasting neighboring shooters (say during a class).
Do not use it if there is overhead cover unless you like LOUD NOISES. The 'blast' is now directed straight up and get reflected back (where before it just went out to the sides).
WHen I tried it not only did I notice it was louder - but the guys shooting next to me also thought it was louder (and they were next to me when I was shooting with the exposed brake earlier!).
The other problem with the device is you get too much muzzle drop. That's right - insted of steadying the rifle or reducing the rise - you'll get the muzzle forced DOWN after each shot. IMHO that is worse than muzzle rise - especially if you're in the prone position.
BTW did I mention I'll be giving mine away to the first person who wants it at the next MD AR-15 Shoot? I upgraded my AK brake to a KKF A3 tac brake!