For self-defense against bears, people or anything else, you cannot beat a shotgun with slugs or sabots. That is a big hole and a heckuva wallup. Especially if you have 3 1/2 inch magnum!
If you need more range than it provides, you are not shooting in self-defense. If you worry about single vs. multiple projectiles, load both alternately (slug, 00 buck, slug, etc). Try that with a pistol or rifle!
I agree: Lose the pistol grip.
A full stock and a 26 inch barrel on a pump or semi-auto with a selection of choke tubes and loads gives you tremendous versatility and fast, accurate handling along with fast followup shots. If you have only one gun with you, versatility is important.
There is nothing immortal about a bear. Put an arrow, much less a slug or sabot, into the vitals and the bear is going down. How hard and fast is what is important in self-defense. There is no bone on a bear a slug won't devastate.
My first bear was a moderate-sized 300 lb black bear with a bow. We were eyeball to eyeball at 25 yards. He chose flight over fight (an arrow has zero knock-down power; so thank God!) and spun to run away. The arrow went in behind his rib cage as he quartered away, cut through his liver and lungs, sliced the aorta off the top of his heart, exited out his armpit, and disappeared into the brush and timber beyond him never to be found. That bear gave one huge grunt like he had been kicked in the ribs hard, made one huge lunge at the same time, and hit the ground stone dead. You couldn't have killed him faster with a 7mm magnum.
Attention: TDR Forum Junkies 
Suggestion, it takes practice to be able to hit a moving target when your nether regions are puckered.
