The 40 S&W was brought out because all the arguments between the 9mm Luger and 45 ACP had been settled and we needed something new to argue about at our LGS
If I were a police officer and from a pure "power" perspective, I'd probably PROBABLY pick the 40 over the 9 just because I think (don't know) the 40 would be better for car doors, glass, etc. On the other hand as a civi I might not want so much penetration?
From a control standpoint, a 40 is a bit more snappy, but nothing I can't handle with 200 pounds of... uh, muscle
. But, what the 40 adds in power takes away from some control especially for smaller framed folks or those who don't have as much range time as they'd like. Which includes me. Trade offs.
I'll say this, when I shoot 9mm +P that tries to approach the 40, it is pretty darn snappy too, and I lose some control. So what does that really gain me?
What do I actually have / carry? 9mm or 45. I just don't want to mess with an additional caliber, and I reload so don't want more components rolling around my workbench.
Am I quite satisfied at the end of the day with my comfort level not having a 40 S&W? Absolutely, and I wouldn't blink any harder in a "gunfight" if I were up against someone with a 40. Oh, and no, I have never had to be in a gunfight and I am CERTAIN I would blink a hell of a lot no matter what I was being shot at with.