Despite all the caliber wars, there's little difference in stopping power, whatever that is, between currently-in-use rounds such as the 9mm, .40, .357 SIG or the .45 ACP.
My question is, if you're talking home defense, you don't necessarily need the bullet performance that the police need unless you think an intruder is going to drive his car up to your bedroom. An intruder will not seek cover and then engage in a set-piece gun battle. He'll try to flee. I'm using Hornady Critical defense in my carry guns. I'm no longer in law enforcement and I won't be engaging barricaded felons or swapping lead along the freeway in a road rage incident.
S&W makes their M&P in .45 ACP and a 13 round magazine is available if legal in your state. That should be more than enough.
Remember that gun and caliber are the least important factors in separating the winners from the losers. Concentrate on mindset, judgment, tactics, and knowledge. an average of one police officer dies every 57 hours in America. Their guns and ammo are state of the art, yet, it didn't save them.
Int'l Assoc. of Law Enforcement Firearms Instructors