For home defense, a shotgun can be very effective from a static position, where your loved ones (if any) are all behind you and you're holding a hallway, stairwell or other area while waiting for the police. I agree that long arms in general are very challenging for any sort of indoor movement, especially where you must juggle a light (so that you don't muzzle anyone you shouldn't by searching with your weapon-mounted light) and closed doors.

My biggest problem with muzzleloaders are the speed of any required followup shots. I don't see any way that they're better than more modern types of firearms, for my uses.