I know little about this subject from personal experience but!! I have just finished reading two books about the 1911 and am about to buy one, like maybe tomorrow.
From what I can discover the 1911 works best in it's origional goverment length, it was designed to be a 45 ACP gun and is best in that round, there are lots of parts for a 1911 and it could be converted to many different rounds from 22LR up to 50GI, the 45 ACP round is a good round, the 10 MM was rejected due to too much kick and may at some point could be rare the 40S&W was to replace it and could be a better choice, the 45 ACP is a more mild round in terms of damage to the gun and could be a better choice. The 45ACP operates at less than 17,000 PSI where the 9MM, 40S&W, the 10MM work closer to 34,000 PSI. The 45 ACP is a big heavy slow bullet that gives the required punch while the lighter bullets travel much faster to give the same punch.
I guess my other thought is we, as Canadians, will likely never have legal concealed carry(in my lifetime), if we did we would carry for a hell of a long time till we needed to defend ourselves against a bad person, or at least I would, carrying a handgun is not that easy, there are nice little rules like banishing a hand gun or actually letting someone see the concealed gun by accident, of course shooting someone who proved to be a good person is a bad thing. Basically what I'm trying to say is we are not Americans. Our guns are likely only to be used to shoot paper, how much power do we really need? I call it too much Testertosa!
JimmieA.