I own many 1911 type pistols and a couple of SIG P220, but for a lighter concealed carry pistol, I have a G38 in 45 GAP. I have the Kimber Ultra CDP II for a concealed carry pistol, but it feels heavy compared to the Glock.
4 or 5 state police departments have adopted the G37 in 45 GAP as their service pistol. I have no problem finding the ammo. I think the GAP is close to the 45 ACP +P in performance, for me it performs very well.
If your going to buy a 1911 type pistol, get a Kimber or a Wilson. Currently no one that I can find still has a production 45 GAP pistol except Glock.
Jerry