Bottom line everythings a trade off. Has been for years.
It has, but many seem to have stagnated, and not kept up with some of the changes, both in hardware, as well as some of the more recent training and social trends.
I dont think the trade offs are as much of an issue as they once were thought to be. Except in maybe a few marginal cases, I seriously doubt the difference in caliber is going to be an issue. All things being somewhat equal in that respect, I dont see that guns of a similar or smaller size, that carry twice the onboard ammo, can be a bad thing, especially if they are easier to shoot realistically with.
Frankly, it's sad to hear a fellow shooter say that "high capacity" magazines are for LE and not civilians.
That likely comes from the hunting, trap, and bullseye side of the shooting community. Trust me, I know, Ive been a full auto owner for over 30 years, and have heard all the usual complaints and insults.
From what Ive seen, I truly believe, that unfortunately, when the time comes, many of "our own" will quickly give up anyone they think might be sacrificial lambs, that may allow them to keep theirs, after all, thiers do have a sporting use.
I have read over and over here about repeat target acquisition and following shots. To me that is less about the gun and the ammunition and more about practice, practice, practice. I do double and triple taps, but I also practice shooting as fast as I can, emptying the magazine, reloading, and doing it again. Not just to see how fast I can shoot, but how accurate I can be shooting fast.
Ive shot more than my share of .45 over the years, and still do on a regular basis. A few years back, I saw the light and switched over to high capacity 9mm's, for most of the reasons discussed here. There is no doubt in my mind it was the right choice. I can shoot faster and more accurate with the 9mm's than I can the .45's, .40's, and a couple of others, and I can do it longer before I have to reload. In some cases, three times plus longer.
Being able to shoot the heavier calibers well just translates to shooting the lighter calibers even better. While the .45's may seem to be less snappy, they really arent, and they do take more time and effort to get back on target quickly with, no matter how much you practice. If you can do it quick with the .45, the 9mm will be just that much easier.