This is a very interesting topic. Kudos to hardcast for starting it. I think his points about practice, being familiar with your weapon and maintaining situational awareness are all valid. I think NoMercy448's points got lost a little bit in that he said "No handgun is a good stopper, but above 380acp, they’re all statistically equivalent." While he gave a few examples comparing a .380 to a .45, his main point was that all calibers above a .380 are statistically equivalent and that no handgun caliber is a good stopper. The author he quoted looked at a few thousand gunfights to determine his data. I would have more questions but that author explained his limitations and he seems headed in the right direction. Hunters life, I wouldn't snub my nose at carrying a 9mm. I recently switched back to a 9mm from a .45 based on tactical training performance at active shooter training. Memtb, a 40 S&W isn't a guaranteed 1-shot stop based on personal experience.

On duty, I have carried .45, .40S&W and 9mm. Off duty, I have carried all of those as well as .380's when I needed extra concealment. I carry based on situational requirements and limits. I'm not trying to put words into NoMercy's mouth but as I understand his posts and the author he linked, 9, 40 and 45 (all above a 380) have very similar results in shootouts and that a person's familiarity and competence with any one of these calibers (and the pistol used) are more important than just the size of the caliber. I also liked NM's linked article as it statistically confirms that if I'm stuck carrying a .380 because of the event requirements, I'm not hopelessly under-gunned. As always, YMMV but that is the freedom we all have to make these kinds of choices.