home defense
I would echo the single shot worry. I would not worry so much about which gauge or what shell, but I think for home defensive purposes, it is vital to have more then one shot. You can buy a 410 pump at wallyworld for about 200.00 or a maverick 12 gauge pump for 159.00.
As as another said, there is nothing more intimidating then the sound of the slide on a pump shotgun.
I now personally like a pistol PLUS a shotgun. Maneuverability can be an issue in close quarters. But - just my opinion.
People sometimes think I am nuts, but I also keep LOTS of ammunition. If Hurricane Katrina taught me anything, it is I had better be prepared to fend for myself and not expect quick resupplies.