I may get flamed for this but it's my experience that the difference between carrying a full-size vs. a "compact" just isn't very much.
Nah, you don't deserve a flame... you're mostly right.
If you use a good belt, holster, and have the correct attire... there are lots of times that a full size is no different than a compact.
Exceptions come mostly when you can't dress to hide the big gun, or if you're going to do a LOT of sitting.
Having said that, I have IWB'ed my USP45 when my normal CCW was "away", and more often have carried my USP40 as it's slightly slimmer. But because I carry IWB at about 5:00, I can't tolerate a big fat pistol of any sort on long drives or "dinner and a movie".
But mostly, I just carry a Kahr P40, which is of course, NOT what you were asking.