Where the 9mm carbine falls short (in my opinion) is the inability to penetrate IIIA body armor. Maybe a few of the faster loads will do it, but not the common ball ammo.
It's one of those longshot circumstances, but if home invaders are wearing body armor, and more are these days, the 5.56 kind of wins in that situation.
Shoot them in the legs or better yet, the head.
