Sure you can carry a loaded 10+1 .45 on your hip with two spare mags, but if you find yourself in a situation where you *need* 31 rounds of .45 ACP, what you really *need* is air support.
I'm of the opinion that it doesn't matter what you carry, as much as it's important to be able to control the gun and hit what you aim at. The .600 Defecalator Magnum looks all shiny and impressive and stuff, sure. But give me a gun I can control and hit the target with every round. I'm happy even with a good .380 auto.
Still nothing beats my M1911, but that's just my opinion for me.