So you think a .45ACP doesn't have substantial enough "knockdown power" over a 9mm? With all due respect, that is not correct.
All gunfight statistics show that it is.
Pistols are all about shot placement and capacity. The more shots on target you make with a pistol the higher the likelihood you will make a shot that is placed in a fatal area. When I was an armed guard in the early 00s I used to carry a .45 because "they don't make a .46." I'm glad i never had to use it because I was stupid and ill informed in how important shot placement was over caliber.