I wouldn’t want to try to stop a drug crazed nutcase with a .22 - but like you said, a gun you can carry is better than a gun you leave behind due to weight. I don’t plan to shoot anyone at a distance. At 10 feet, and after 10,000 rounds of practice, hitting someone in the head wouldn’t have been hard.
I don’t carry now, but would seriously consider a .22 if I get my concealed carry permit. I lugged a 9mm around in Afghanistan, and truly enjoyed taking it off when I left!
The M9 is 33 oz, which is a lot to carry around all day. The 9mm Glock 33 is 20 oz. There’s lots of light subcompacts that have decent stopping power.