9mm is enough for a SD weapon. Remember,,, pulling a pistol is of last resort. Avoid battle at all cost in public. Even if it means seeing things you don't like. In your home do as you wish. I can drag out a .44 mag if I thought I needed it. Fact is I don't. I could blow a hole in the perp and kill my neighbor or a person in a car passing by. Not to mention the children by day in the park next to my house or the teenage thugs there by night that know better than to challenge this home.
My carry is a PF-9 that I really like. Small and hurls 124gr bullets with the best of them and small. If they ever make a good priced .45 ACP the size of the PF-9 I will have one. But the .40 is a no go in this house. If I wanted to go through life with a brick strapped to my body I would do so. But that is not going to happen.
If I lived in the northern USA I would be looking to cut down and rework a CZ-52 type pistol that could deal with heavy winter clothing. As it is now the Cz-52 spends most of it night on the night stand. Reason being. Not the round count. Not it's ablity to throw rounds that splatter and destroy flesh or make big holes. I keep it there with Wolf idiot HP's because I shoot it better than any pistol I've ever owned. And I am working up my own loads for it.

If you crash into my house with my old crawl space floor. I can hear where the perp is and the round will do a great job of shooting through walls, 2x4's, lath and plaster.
Just my .02 cents.