Sorry for expressing a different viewpoint, but unless you are shooting expensive slugs out of a rifled barrel with a good scope, the maximum effective distance of any shotgun shell is only about 60 yards, which is about the same distance as a grown man can hit a softball, or a college quarterback can throw a football. Way too short, in my opinion, for anyone to rely upon as a primary arm in any long emergency situation. Yea, it would be nice to have one, but its use is limited (except in a close urban environment.) In any such situation, I sure wouldn't be wasting shotgun shells trying to hit running rabbits, flying birds or jumping squirrels. I would use a .22 LR for this, and only take shots when they were standing still.
Just my thoughts.
Mannyrock