"No penetration, no incapacitation."
Correct.
See:
http://www.firearmstactical.com/hwfe.htm (Peruse the paragraphs under "
Ammunition Selection Criteria").
"People often hide behind cars, doors, walls, etc. Heavy clothing and jackets can also slow down a bullet."
Exactly.
Where penetration of intervening barriers is called for, the
10mm Auto bested both the 9mm and the .45 acp in the FBI's testing of barriers frequently encounter in LE, e.g., wood, various metals and auto glass. It also proved to be the most accurate caliber of those tested.
See Hall's report discussing this:
http://www.totse.com/en/bad_ideas/guns_and_weapons/10mmpist.html
"The .45 would not have even done this well in the same situation [Miami, 4/11/86]. AS the range increases the effectiveness of the .45 ACP goes down dramatically."
Sheer speculation as to the .45. However, range and energy dissipation aren't issues for the 10mm, even when loaded to less than full-strength. Unfortunately, the 10mm wasn't an option for Bureau agents in 1986, and Detective Crocket was busy elsewhere. For that matter, at the distances encountered in the Miami shootout, even the 180gn .40S&W would have penetrated Platt's vitals (pulmonary artery, lung & heart) further than did the 115gn 9mm STHP, which proved to be a miserable failure when needed most.
"2. Recoil. Most people simply do not shoot the full powder .45acp loads as well as the milder recoiling 9mm."
Way overstated. Some people find a .380 tough to hang on to. Then there are females, like Tamara & others, who have no problems shooting the more "energetic cartridges." (See, e.g., M&S, "Stopping Power" (2001), pp. 272-273). Then again,
some people are wusses. So what?
"3. Capacity. ..."
Only an issue if you plan on missing a lot. Many don't, which is why single-stack 1911s holding less than 10-rounds are still popular.
"4. Size and weight. ..."
Possibly that's an issue where large-framed all-steel autoloaders are involved (which some people still favor
), but with the proliferation of the smaller polymer Glocks, available in all common calibers, it's become a nonissue.