I once read an article that mentioned a study of Prison inmates... it went something like this ...
"
What is the one thing that would stop you dead in your tracks if you were doing something you shouldn't be doing ? "
The resounding answer was " The sound of a 12 Gauge pump action "
Most of what I've read has said that for "purely" home defense a Short barreled (18" ) tactical shotgun ( No stock but pistol grip for maneuverability ) with Buck shot or bird shot ( to avoid over penetration) is the best Home Defense weapon there is. The sound alone is enough to scare an attacker off. Also the fact that in a high stress situation and a moving Attacker , a shotgun gives a bit more room for error.
If I had wanted one for STRICTLY that , I would not have gotten my Glock. I would have bought a shortgun. But I wanted a CCW/Target Pistol as well to serve as both.
I have often though considered trading in my .22 Magnum for a Mossberg 500 ( interchangeable barrel lengths for home defense or Hunting ) and adding a tactical Pistol Grip to it.
Mossberg 500 Cruiser
More review info:
http://www.firearmsfirst.com/?p=11