Lots of help again... Thanks
As always, you guys (gals?) are GREAT. This is by far my favorite place to go for gun advice.
Perhaps I wasn't clear enough in my original post. I have NO INTENTION WHATSOEVER of getting rid of my Sig P220 Sport .45. I love it, and I will someday leave it to the one of my sons who'll best take care of it (probably my oldest who's in Air Force Special Forces and has both a professional and personal interest).
I'm shooting around 120 rounds per month (I know, not a lot), but I imagine that going up to 150 rounds per month or so if I get a second gun. The .22 slide for my P220 is intriguing, but (am I crazy or just immature?) the idea of shooting .22 ammo from my Sig is just not very appealing to me. My guess is, after calculating the increased shooting but different mix of ammo, (and after reading your fine advice), I'll probably save around $150 per year in ammo costs (if I go with a 9 mm) AND shoot more AND get a new gun. Sure, it'll take a few years for the savings to even out the cost of the new gun, BUT I GET TO BUY ANOTHER GUN!
It seems, based upon your responses that, with this approach, 9 mm is the way to go. What 9 mm would you recommend given that I don't wish to spend the kind of money I spent on my Sig? Also, how does one find trustworthy sources for police trade-ins?