Yes,
if your shotgun is an O/U birdgun with a 32" barrel, then you're going to have problems moving around in your house. However, from someone who
has cleared buildings with a shotgun, a 18.5 to 20" with or without a full stock makes an excellent CQB weapon and is very manuverable
if you practice with it.
The real question is not what hardware to use, it is what job do you have to do?
--Are you in a townhouse? A development of concrete-block homes? A farmhouse on 40 acres?
--Is the farthest range of engagement under 10 yards and inside? Over 10 yards and inside? Out to 100+ yards and outside?
--Do you live where the PD will respond quickly, or are you going to be on your own for an extended period of time?
--Do you live alone? With a wife or girlfriend? With kids in separate rooms? On different floors?
--Do you have the training, skill and determination (a.k.a. foolishness) to go goblin hunting in your house or are you planning to bunker down in a defensive position and call for help?
--Is your most probable threat a burglar armed only with a screwdriver or crowbar? 1 to 3 home invaders with knives/guns looking for soft targets? An armed and body-armored gang that is specifically targeting your house for an assault?
For
me (no kids, armed wife, single family home with wood/plaster walls, plenty of training, facing a non- or lightly armed burglar threat, <5min PD response w/ 1-5 officers depending on the time and day) the solution is a pump gun on a sling as primary with a semi-auto pistol on my belt as backup (Federal Tactical Flitecontrol 00 buck, and 180gr HP) and wife with a .357 and a cell phone. I am going hunting, I know my terrain, and I have practiced moving/clearing rooms in my home (then again, I have "issues"
).
In my opinion, 12ga offers better odds of hits on target, especially if you have not practiced engaging a moving person while dealing with the stress/fear of a life and death situation (where your ability to aim, focus on sights, hold your weapon steady, etc might be compromised). Also at close range you're potentially putting a lot more lead with a lot more wound channels into a torso maximising your ability to put the threat on his back
immediately and on the first shot. A .223 to the torso
will put a threat on his back eventually (or with multiple hits) but at close range you may not have the luxury of time on your side. If the recoil or size/weight issue of the shotgun and the overpenetration of a rifle still puts you off, I'd recommend a carbine-type weapon (at work its an MP5 chambered in .40). It's lighter, still excellent for CQB and packs a punch that can put a threat down. On a side note, I do not advocate PG shotguns or collapsable stocks for one simple reason--
if the goblin still manages to get close in or
if my weapon fails for some reason, the buttstock of my gun suddenly becomes a great weapon in it's own right and I can close with the enemy with a decided advantage over just a barrel (I think I already stated that I have "issues").