I'm not an SME and I may be totally out in left field here, but here are my thoughts:
I like a pistol for investigating the "bump in the night" kinds of things. As has been mentioned elsewhere in the thread, it's much easier to conceal when answering the door (if it's the cops, neighbors, etc knocking). My personal nightstand pistol is a Glock 17, AAC Evo-9 suppressor, Surefire X400/DG switch, 17 rounds of 147 HST. This is also the firearm with which my wife is most comfortable (she's not opposed to guns, but has no real interest in training) and I view the laser as a "this is about where the bullet is going to go" indicator for someone like her who doesn't train enough for sights to be a reality at speed/in the dark. She simply has to pick up the gun and the light and laser are automatically turned on with the DG switch.
Standing up next to the nightstand is a Benelli M1S90, 12ga, 18.5" cylinder barrel w/rifle sights. It wears a Surefire forend, holds 7 rounds in the tube, one ghost loaded on the carrier, and one in the chamber. These are all Fed LE1321B with another 7 rounds of the same on a velcro side saddle. The two rounds on the right sight forward of the ejection port are Fed Deep Penetrator slugs. If we awaken to indicators of impending violence, this is my primary weapon to secure the hallway long enough for my wife to retrieve our son and retreat into the bedroom with him and the pistol. I still have a hard time getting over the fact that with one pull of the trigger I've effectively dumped the magazine of a Glock 19 into my target (and it easily maintains fist-sized groups inside of 25yds...pic below was 25yds). Not only is a single round very effective, but I've got nine of them before I need to reload. If for whatever reason the fight moves outside and I need to disable a vehicle (maybe they kidnapped my son, who knows) a quick slug changeover should do the job. I have plenty of confidence in the reliability of this M1 through using it (with a different barrel) to shoot sporting clays and (in this barrel/mag configuration) to shoot 3-gun.
If there's some sort of civil unrest or if I just get a bad feeling, I swap out the shotgun for a suppressed 10.3" SBR AR15 with an AAC M4-2000. The rifle's magazine is loaded with 28 rounds of 55gr 5.56 Gold Dot. It wears an Aimpoint T-1 that stays turned on and a Surefire X300 Ultra. This is the more capable gun all-around, and if I knew I was going to get into a gunfight, this is the one I would want to be holding. As great as it is, I still feel that the single round wounding capabilities of the Benelli are better
for a purely in-the-home scenario.
As far as armored enemies, (assuming that despite incredibly low odds, it has happened to me) it seems that the force of energy from the 12GA buckshot round delivered COM would perhaps pause his fight long enough for me to deliver a second round to his non-armored noggin. Especially since I'm shooting an auto and follow-up shots are quite fast.
Thoughts?