I'd use my PC9 for home protection,,,,,,if it wasn't so much fun at the Range!
I'm well-beyond 'hundreds and hundreds' of rounds sent downrange. (Doubt I've passed 5K, but I'm probably a lot closer than I think.)
I know what it likes to eat without fail, and, in my hands, it can be very accurate @ 50 yds. I also have a Suppressor for it, but I don't use it much as doing so at a PUBLIC RANGE kind of defeats the purpose.
An SBR or an AR platform in general, for me, may not be as good a current fit as it's been years since I've shot any of my AR's. Perhaps a few weeks at the most for my PC9.
Does that mean I'm without Home Protection? No, not in the least, as I have multiple readily-available alternatives that I own/shoot on a regular basis.
Perhaps some day it will be regulated to Home D use, but that day doesn't appear to be coming anytime soon! =)