In my experience the 24" AR is an unwieldy beast. Likewise, a 20" bull barrel is excessively muzzle heavy but at least it's more manageable. I've found that the shooter doesn't notice much difference in muzzleblast(20' vs 16") but spectators certainly do. Removing the muzzle brake will help with the side blast and make it easier to be close when the rifle is fired.
My 16" carbines lose around 200-300 fps compared to 20" barrels but this isn't a valid comparison since no two barrels will give the same velocity even in the same length.