I can only cite experience gained in 18 years of civil-unrest confrontations, including being (unwillingly!) present at rather more than 100 gunfights, some as a participant, most as an observer. I've also been shot more than once, all with 9mm. or lesser calibers - and I'm still here, which might say something...
In general, I saw 9mm. (hardball and 1980's-vintage JHP such as Winchester Silvertip, Federal 9BP, etc.) produce poor "instant stop" results. Frequently, half-a-dozen or more rounds would be required, and even this did not guarantee that the target would be out of the fight immediately. I saw more than one occasion where a machete-wielding BG took six or more rounds of 9mm to COM - and they were good hits, too, shredding heart, lungs and other organs - yet still survived and stayed on his feet long enough to eviscerate the shooter. Not pretty...
On the other hand, major calibers (.44 Special, .45 ACP and Colt, etc.) tended to produce good stopping results with one to two hits to COM - and it didn't seem to matter much whether JHP or hardball or SWC rounds were used. The targets seemed to go down faster and harder, and were much less likely to get up again and be troublesome.
(.357 Magnum loads seemed to perform about as well as the big bore stuff, provided they were full-house loads. The 158gr. JHP's seemed to over-penetrate with monotonous regularity, but still did a number on the target, while the lighter JHP's were OK, but sometimes not fully effective on hopped-up attackers. For this reason, I prefer the Winchester Silvertip 145gr. load in my .357's today - "best of both worlds" sort of thing.)
I know and accept that current JHP technology has improved tremendously over what was available in the 1980's: but as a result of my experience, I remain viscerally distrustful of the 9mm. as a "stopping" round. Sure, it's as lethal as any other handgun round: but how quickly?
I tend to want my handgun "stopping" calibers to begin with the numeral "4", with the exception of .357 Magnum, where I'll take a full load of good 145gr. Winchester Silvertip JHP anyday, and feel very comfortable with it. For backup, I'll take a 9mm. or .38 Special compact handgun, but I won't fully trust it - that's why it's a backup to something more potent!
As to rate of fire: I want to hit with something effective. Given that requirement, I'll practice until I'm sure I can do so. I can certainly obtain hits faster with a lower-recoiling round, but if those hits aren't necessarily as effective as bigger calibers, why bother? Practice, practice, practice...