I always have my Polish P-64 in 9x18 someplace. In the summer I carry IWB with a Sig P250 sub compact 9mm and one mag. When it goes a little colder, or I'm wearing a jacket, I carry that Sig and two mags or my XD compact 40 and an extra mag.
I also wear a Taclite concealment vest. In that I'll carry the XD and two mags with the P-64 inside my waist band. I like that vest simply because drawing in a seated position is a breeze.
Having been a C/O for 19 years, I know what these guys are capable of. I've seen it take 5 officers to take one down when he is simply in a rage. Of course we have no weapons of any kind. That gives me a special view of these thugs, one that not even a cop gets. Not just the force part, but the total spectrum of conduct.
Some years ago A cop told me that I didn't need a gun off duty. Of course he told me he carries his. I told him that a lot more felons would recognize me on the street than would him, and more than a few might want revenge. He rejected my argument.
Most of these stories are of cops in fire fights, often running fire fights. In an SD situation I have no desire to "win", no macho desire to prevail over an opponent. No, in a running fire fight it's me running the other way. I'm sure I'll be seeing that guy again.