AFAIK, the 1911 is not safe to carry chambered and with the hammer lowered? Plus if you slip while doing that, it would fire, at least that was my impression with models I'd tried?
How many have you had go off when carrying that way? I've never heard of a single such incident, although I have no doubt it has happened ... somewhere, some time.
It isn't a recommended mode of carry, but only because the only "decocker" is your thumb and forefinger, and any time you are handling the hammer over a live round there is a chance you'll slip and drop the hammer. However, I know several very competent
pistoleros who see nothing wrong with lowering the hammer manually. Of course, most of them also tinker with Single Action Armies. I've never quite understood why it's no big deal to manually lower the hammer on a SAA, yet it's a major
faux pas if you do the same thing with a 1911.
Once the hammer is down on a 1911, it can't go off. The firing pin is an inertia pin -- it isn't long enough to make any contact with the primer with the hammer resting on it. It needs to be whacked by a falling hammer to shove it into the primer.