If you are concerned about a private citizen self defense situation, historically the average situation involves approximately 2-3 rounds to resolution at close distances...While I'm not a real fan of the .45acp in general, there is no denying that it is much more effective than the 9mm when it comes to absolute knock down power at close ranges..
LEOs tend to go high round count due to two factors, when involved in a critical situation, most are not that great of shots under non-stress situations and when stress is involved they get even worse, and secondly, their critical incidents can turn into a drawn out 'run and gun' situation where they are pursuing a suspect over a more than average distance and the availability of an adequate amount of ammunition may be an important factor in the outcome..
If you are concerned about the personal comfort of a 1911, there are other .45acp handguns that are much more comfortable for some to shoot from Glocks, to HKs, to Sigs...