Do I (as a handgunner) own and shoot ARs/shotguns? Why wouldn't I ?
The only reason I can think of would be personal preference.
As it turns out, no, I don't own/shoot an AR. Used to, but sold mine back in the late 80s, when my $450 AR brought $900! Haven't gotten another one. Don't see any need, or point. I have a Mini 14 that should work just as well as an anti mutantninjabikerzombie weapon. And I don't use the .223 for varmints, I have other guns for that.
Shotguns? a half dozen or so, all 12ga, except for one bolt action .410. Don't shoot them much any more, but considering I used shotguns extensively for recreational purposes for close to 30 years, I figure I haven't, and won't forget how to use one.
All most people need is to hear that distinctive pump sound come from the other room.
Is there even one documented case of this actually occurring?
Does personal experience count as documented, or is it merely anecdotal? Because I have had it happen to me. And I was the one hearing it! Complicated situation, involving a jealous girlfriend, long, long ago. But I can tell you that the sound alone was enough to make me seriously rethink my priorities and planned course of actions!
Tactical defense plan involving AR/shotgun? Not hardly. First off, if I had one, why would I publish it on the Internet? Second, AR, (and all rifles) are very poor weapons for home defense, as defending your house and self is more about repelling boarders than anything at extended range. So a rifle is a poor choice. Better that no gun, but not first choice by a long shot (pun intended). I do keep a coach gun with some buckshot in the buttcuff, as backup, but my primary home defense tools are which ever of several handguns I reach first.