My peace (not piece) of mind comes from having one in the chamber. Because I have no desire to rest in peace any sooner than I have to. People who don't carry with one in the chamber need to understand they are going to be in a bad way should they ever need to defend themselves. I've had one self defense situation where I pointed my Glock 23 at two thugs attempting a break in on me. They bolted, but if they hadn't, I was ready to engage immediately.
There is a big difference in someone breaking into my house, and me getting involved in stopping an armed robbery. I had rather police handle the armed robbery. No time to wait on police if someone is breaking into my house.