Let me begin my comments by saying that each of the three pistols that this fellow mentions are fine handguns, and a case can be made for each one as a personal-defense firearm. Having said that, let's look at a serious problem that should be immediately evident.
While all three pistols are semi-automatics, they represent three distinctly different types of actions. The 1911 is a single-action with a short trigger pull and two external safeties. The SIG is a single-action/double-action pistol with one external safety. And the S&W is a single-action that is often referred to as "double-action-only," and it can be had with or without external safeties.
So, in the middle of a gunfight, this worthy shooter has to remember if he needs to push down on the safety–or push up–or does it even have a safety? If that is not enough, he has to deal with three different types of trigger pull–actually four, since the SIG operates in both double- and single-action. If that is not enough, the round count is different on each pistol, the trigger reset is different on each pistol and the grip shape is different on each one. What we have is a recipe for a guy who happens to owns three very nice pistols to lose a gunfight while trying to remember which gun he is holding and exactly how it works.
People who have not been in a gunfight cannot imagine the amount of stress this sort of confrontation puts on a person. The mind should be focused on awareness, recognition and the front sight. Managing the defensive pistol should be second nature, something that can be done without consciously thinking about it. That usually only happens when you live with a particular handgun and love it and learn it like you would a sweetheart.
Many of us are fortunate to own and shoot quite a number of very fine pistols. We like guns; we enjoy them. That's all well and good, but carrying them on rotation for defensive purposes is usually a mistake. In a gunfight, it pays to focus on the bad guys, not on trying to run your gun.