It seems like it would be rather big, somewhat unwieldy, and something you wouldn't be practicing with a lot, and even not able to practice with at action shooting matches, for example. I'd also be concerned about availability and cost of ammo. So, it's kind of unattractive with these assumptions in mind.
Anyway, the scenario I envision as most likely for me is:
-- at least 2 intruders
-- already inside my home before I know it
-- at night, and
-- very close by the time I see them.
I don't see having both a) the ability to determine the offensive level of the threat, AND b) the ability to then choose the weapon. So, I have to already have the right weapon for worst case.
I don't believe any of us has as our objective to kill anyone--the objective is to stop the threat. Inside my home, I believe the law has sided with the citizen in saying I don't have any obligation to determine first if it's a lethal force situation, I'm okay to assume that it is (Colorado). I think the only smart thing to do is to assume the threat is a deadly one.
I need something that stops the threat--and keeps it stopped--to the degree practical. I feel the need to have the first intruder stop and stay that way while I look for other threats. There's no guarantee of course with any weapon, but what would be very appealing to me would be a short-barrelled shotgun capable of reliably handling the short 12 ga ammo, such as the 1 1/2" shotshells from Aquila.
So, for something bigger than a handgun, the long-proposed KelTec KSG, designed to fire the 1 1/2" shotshells, seems close to perfect. It could potentially be used in some action shooting (3-gun maybe) sports, but at least in IDPA-style side matches, and it would fire readily-available and relatively inexpensive ammo to help ensure adequate familiarity.
I know none of these ideas helps for the market you're looking at--those who want/need something other than a firearm. I just don't see a weapon that's designed to be nonlethal as a good option for home intrusion...the lethal ones are uncertain enough as it is.

