I get the love for ARs (I've got some) but for strictly "home defense" indoor ranges, I'll stick with a 18-20" barreled shotguns. For protecting a larger property where outdoor ranges come into play, then an AR makes more sense. Just my opinion.
Pistol cartridge carbines generally provide pistol cartridge ballistics, but shooter has an easier time shooting accurately............which is a big deal, and justification for the platform IMO.
I've looked hard at tactical shotguns, too, but can't warm up to them, either. Even a quality unit, like a Benelli M4, will be longer and clumsier than an AR, and hold fewer shots. The M4 is pretty spendy, too.
If the bullpups like the Kel-tec KSG were known to be reliable, they might be an option, but so far I'm not willing to shell out the cash to be the guinea pig.
Benelli makes great autos, but aren't the only reliable autoloader out there. Certainly one of the most expensive though.
Regarding ammo capacity, there's probably a security blanket feeling that comes from a 30rnd mag, but a shotgun with a 6-10rnd capacity (and more ridding outside) is no slouch for HD scenarios. If you accept that most threats engaged with a carbine will receive multiple rounds (on the trigger until the threat drops) all of a sudden your 30rnd mag, even if divided by a conservative three shots, gives the user ammo for 10 targets. But at HD ranges, the trauma from a single round of buckshot will likely suffice. Different wound characteristics, but lots of damage nonetheless.
There's always a doomsday scenario where a whole biker gang comes into your home at the same time, but realistically (at least for me) 8rnds in the gun with more riding on it is enough to not feel under-gunned. YMMV, and that's OK.
