I sort Of Disagree With Part Of That
This~~~~~~~~> "It will also be harder on the gun. Even if the gun in question is rated by the manufacturer to be suitable for +P ammo, the gun will wear out sooner."
Naturally if you shooting lots of +P you should install a fresh recoil spring more often or absolutely move up to a heavier weight spring.
Most modern semi-automatics can handle +P without any accelerated wear.
The 1911 especially.
I remember one old gun test where steel .45acp cases were used and the .45acp was loaded all the way up to .44 Magnum pressures and velocity with no undue wear to the firearm.
There WERE some problems associated with the steel cases sticking in the chamber. That problem was solved by lightly Teflon coating the cartridges.
Remember that +P semi-automatic in .45 acp can only withstand so much increased pressure because normal cartridge brass in .45acp is comparatively weak in the case wall. Too much pressure and the cartridge case walls will blow out upon extraction.
SO......any +P or +P+ loading in .45acp is still well within pressure limits of what the Colt 1911 can handle without suffering any physical damage to the barrel, slide, or frame at all.