I personally own a 14" Mossberg 590A1 and also use one on duty as a LEO. I've also been issued a Remington 870 in the past. I've primarily used pump shotguns in both my LE and military careers.
Mossberg shotguns are beasts...sturdy and tough, they'll eat anything you feed 'em. I am not a fan of a pistol grip on Mossberg shotguns because it is a very difficult reach from pistol grip to the tang safety. A pistol grip is better suited to a shotgun with its safety located on or near the trigger guard, like a Remington, Benelli, etc. Just my 2 cents.