Thanks for posting, this is an excellent discussion topic.
I'm glad to see you are rethinking your regular carry gun. I know a lot of folks carry a .380 and some even a .32ACP, but the undeniable fact is you are at a huge disadvantage against someone with a larger caliber weapon or multiple attackers. This disadvantage isn't limited to caliber of the gun. It includes a very short sight radius, small sights, limited capacity and less control due to the small grip.
Our club ran a BUG (back-up gun) match in December and it was a real eye-opener for a lot of shooters. Kel Tec, LCP, LCR, SIG P238, Bersa, PPK and most other tiny handguns were well represented. Many guys/gals shot 3" 1911's also and some M&P Compacts and Shields. A large number of people carrying the first 6 categories decided to change to something else, either a full size gun, or at least one of the 3" 1911s or M&Ps. Shooting an IDPA match under somewhat realistic conditions drove home the fact that pocket pistols are designed to be firmly screwed into someone's ear before pulling the trigger. Engaging someone even at 7 to 15 yards and/or multiple attackers, sometimes on the move (you'd better be moving in a fight), brought home the reality of the precarious position one is in when defending their life with a mouse gun.
I realize many will disagree with my position, but when you talk to people who have been in a position to have to use a mouse gun in self-defense, my thoughts are widely accepted. My youngest son is among those folks. (He was carrying a Walther PPK instead of his 45ACP Commander.) I'm 5'9", weigh 175 lbs and I carry a 5" 1911 every waking moment and it conceals just fine.
Chas.