Have you ever shot a shotgun with a pistol grip _only_ (and not the conventional pistol gripped butt stock)? If you have and you felt comfortable with it/were able to hit your target then disregard what I am about to say. Or I may have mis-read your post and in fact you are refering to a full pistol gripped stock.
I personally have had, and seen more people have problems with being able to effectively use pistol gripped only shotguns. Without *EXTENSIVE* practice it is extremly difficult to hit targets with these types of shotguns. I would say get a more conventionaly stocked shotgun even for home defense. If you like the pistol grip, there are full butt stocks out there that offer true pistol grips as part of their makeup. Choate used to make one of these types, I believe that they still due.
It's amazing what a large group of stupid people can accomplish.