Wow! EXCELLENT information Marcus, thank you very much 
I live in Asunción, Paraguay. Most countries in south america have laws that forbid the use of JHP ammo by civilians.
If restricted to non-expanding ammunition, what are the choices to improve terminal performance for defensive use?
Going to a larger caliber seems like the obvious choice, but possible drawbacks would be you don’t like the available plattforms or their magazine capacity.
You have mentioned in the other thread that FMJ FP is somewhat superior to rounded ogives, specially pointed ones like the ones used in 9 mm. Does increasing the velocity or bullet weight does any good? Faster bullets penetrate metal sheet better, but normal 9 mm FMJ has plenty of penetration (even excessive) in human tissue, and energy does not kill. Going to a heavier bullet? momentum does not seem to kill either… only advantage may be an increased capacity to break bones.
In many countries around here civilians are restricted to 380 and 38 spl, higher power calibers and larger bores are not allowed.
The 380 ACP seems to be about a marginal “manstopper”, but what about revolvers? the 38 spl can be easily hot rodded to +P or even +P+ specs in modern steel frame revolvers.
In 38 spl, with solid bullets, is there anything to gain with higher velocity and/or bullet weight, above the normal (pretty anemic) load of 158 gr @ 750-800 fps out of a 4" barrel? If you handload, the choice of bullet profiles is larger for revolvers, you could use a FP with a large metplat, a full wadcutter, a LSWC, different alloys, etc. in many weights.
Finally, you said very wisely: “When you take in the big picture, the differences between all the handgun calibers and loads are quite small in comparison to the improved effects you get from using a rifle or shotgun.” Perhaps I worry too much about all this and would be better spending my time training…