crebralfix,
"Both weapons require training an a variety of contexts to use effectively. The "unwieldy" nature of a rifle in the home simply means that poster has no idea what to do with a rifle. Obviously, no Marine would ever enter a building in Fallujah with an "unwieldy" M4 carbine."
They also wouldn't enter a house alone. One man breaches, then there is a buttload of marines in the house. When you are alone, clearing techniques are different vs. when you are with a 5 man squad that has a couple of m4's, possibly a SAW or 240G, and possibly another with a .203. They also have body armor, with sappy plates, and kevlar helmets. He rounds the corner, and you have to pick your shot and still worry about the other 5-6 guys coming through who are going to kill you if you shoot.
In your home, you aren't in body armor, you aren't wearing a brain bucket, and you don't have 5 guys covering your buttocks. Unless you are going through sideways or backwards, your gun is coming through a door way first. If BG is beside the door, it's a free head shot as you walk through.