More details on what you want and are use to using would be helpful in giving you suggestions.I'm thinking about a 9mm for off duty/backup. Looking at the Kahr. Thought? Suggestions?
In 9mm A Glock-26 or Glock-19.
If you run a glock 22 or 27 for duty, then I would go with a glock 23 and use the 27 as a backup permanently with 22 mags on the belt. That way you can have full size mags with compact/subcompact guns that will use those same mags.
I carry a glock 26 with g17 mag on my belt. When I carry my g19 (haven't for 6 months...step dad has it for his security gig) I carry it and a 17/19 mag on my belt.
I wouldn't want to have different mags to worry about, I would want them all to work in every gun I'd have on so as to not grab the wrong one and try to chamber it.
You bring up a lot of the things I've already thought of. The reason I have the 27 is the ability to use other Maggianos and the fact that it operates just as my duty Glock. I guess it's just wishful thinking that I could get something lighter and easier to conceal. You're exactly right.