What's wrong with a Slimline G36 if you stay w/the .45?
Otherwise maybe a Glock compact or subcompact in a either a 9 or 40?
I have a .38 S&W 642, which I've been told by a NYC policewoman, is their BUG. I wouldn't be entirely happy if it was my main CCW. Only 5 shots and more recoil than the semis.
Although the G36 is 6+1 you can always carry an extra mag. Plus you are with the larger cal.
Just my .02 cents.