I really like my Sig P320 Compact(two tone). I went a few years without owning a Sig Sauer and I missed having one so much. I would like to try a Sig P365XL. I've read great things about them...Yes in deed, you can change so much with both Sig P-320 ( includes M17 & M18) and Sig P-365 to ones personal desires as they have a FCU.(that has the only serial number on the pistol) We all can thank the US military as they wanted to update their berretta 92 for a modular FCU in 9mm and afterward Sig got the contract, the market for P320 exploded just as the P365 is still exploding as we speak
As far having to carry a different firearm because of injuries, it does suck. I had neck micro fracture surgery and then 2 years later I had Quadruple Bypass surgery. The only firearm I could carry for a while was a S&W 638 Bodyguard(which I still have to this day and will probably be with me until I die).
Before I got the P320 I got a S&W M&P EZ in 9mm and it's a good semi-auto for old people... I'm seriously considering getting the S&W Equalizer(EZ with higher capacity magazines and different slide serrations. It looks like a cross between a EZ and Beretta APX...)
I find myself carrying the P320 Compact most often, even if it gives me a little neck pain once in a while. I've been experimenting with chest bags(or wearing a fanny pack across the chest). So far I can carry the P320 (and spare 20 round magazine) in a chest bag/fanny pack, with no pain. I'm thinking a P365 XL would be just as comfortable.
I'd prefer to carry at minimum a 9 mm or (38 special). When I see posts of 1911s, which I enjoy, it does kind of make me sad because before the surgeries I had at least 1 1911 in my arsenal, many times I had several. I miss my Para Ordinance P14-45...a lot...