The US has bounced back and forth between large caliber (.44 to .45) and small caliber (.36/9mm) twice, once during black powder days, and again with smokeless powder.
No doubt, the .45 can have better terminal ballistics. The .36 is easier to shoot in some situations.
For a standard pistol range of 20 feet.
Say a .36 has a .9 probability of hit and a .8 probability of kill, given a hit.
Say a .45 has a .8 probability of hit, and a .9 probability of kill, given a hit.
The combination of each is the same, .8X.9=.72 or 72 percent probability of kill for one round. Shoot two rounds and you get. Pk= .72+.72-.72*.72 =0.9216 or 92 percent.
Cut the distance to 10 feet, and Probability of hit goes up, but Probability of kill given a hit stays the same.
.36......Pk= .95 X .8 = .76 for one round, .94 for two rounds
.45......Pk= .9 X .9 = .81 for one round, .96 for two rounds.
What happens is if your enemy gets closer, the .45 gets better.
Your mileage may vary. the above is one way to think about things.
The question is what happens when you get closer?
I doubt your hit probabilities.
A .45 is no harder to hit with or control than a 9 if you aren't afraid of it. My son, at 5 feet tall and 100 pounds was shooting a 1911 with either hand as well as he did a .22
Go out to a local IPSC shoot and look at the size of some of the shooters using .45s, it's all about the attitude.
So9