Never having fired a 14 inch barrel shotgun; I have to wonder what the muzzle blast is like to the shooter, particularly indoors? I've fired 18.5 inch ported shotguns if those could be used as any sort of comparison.
I'm aware that shotgun powder tends to be fast burning, maybe it's NOT like a grenade going off? People obviously use and like these things but it seems there would be a downside here.