In 9 years of special operations service, through the police academy, and in multiple real gunfights, I have never once rolled. It may be faster for getting in and out of cover on your belly, but 1) you won't be able to roll with your LBG on anyway, and 2) in general the value of prone position firing is negated by the immobility it causes. But then, unless you are a cop, or at a pistols only game, the need for a pistol is almost non-existent too.