Good grief! All this guy wants to do is to protect his home- he isn't planning on taking Mount Suribachi!
Talk about overkill...
My suggestion of the CAR was a general one for a long arm. I would not suggest anyone except an entry team member investigate that "bump in the night" with a long arm. Too many weapon retention issues, as well as problems opening doors, using a cell phone, target ID, etc.
Technically, I wouldn't recommend anyone do room clearing alone, but, as someone else mentioned, they should retreat to a safe room with a cell phone and firearm and wait for the cops.
In reality, however, most people will investigate noises in their home at night, unless it is obvious that there is an intruder.
As for the CAR, I would leave that for any civil unrest scenario, should it occur. Or just fun. My main point is that I believe that the shotgun is vastly overrated for anything other than sporting uses. And those on the cutting edge of CGB/firerams tactics seem to agree with me.