This has diverged a bit... I'm pretty anti-shotgun for home defense. It's better than nothing though. They're generally somewhat heavy, long and recoil is stout. They're more difficult to wield in tight quarters, slow to releod/rack, and require more motor skills to operate than anything else. Shotgun "spread" is a complete myth at indoor ranges. I think the ideal defense gun for most is a "normal" caliber pistol with a light attached, and a second light nearby. Second light is for investigating the bumps in the night that may or may not be friendly; the pistol light is for when you actually need to shoot.
Those of you who think racking the slide on a shotgun/semi-auto is going to scare people away: Think about druggies. If dude has pumped himself full of god knows what, do you think he's going to be scared shitless from some annoying sound that has just given your position away? Unless you have children who run and jump and mess with shit and do whatever else it is that children do in your house, I'd leave the weapon chambered.
5.56 is far less likely to go through all your walls than either pistol or buckshot. And it will stop anything likely to walk through the door. The pistol is only for when you can't carry your rifle.
SA-20 semiautomatic 20 gauge is a fine home defence gun 37 inches long, female friendly recoil, no racking needed.:up: