Yeah I agree with the sentiments above - this thread has been quite an interesting read about the comparative ballistics of .40S&W and .45ACP
Of course nothing that hasn't been discussed before, ad nauseum, so I wonder if it won't get locked.... (perhaps my stab at an IBTL? I love IBTLing
)
Anyway, to address the issue, I have a SIGPRO SP2022 in 9mm, an HKP2000 in .40S&W, and a 1911 in .45ACP. I love all three, I think they all have specific strengths that make each ideal for the intended use.
The 9mm SIG stays in the car. With one extra mag, that means I've got 30 rounds of ammunition in case something happens when I'm on the other end of town and may have some difficulty getting home to arm up. The SA/DA trigger is both immediately accessible for carjacking defense etc. while also providing a nice, light SA pull if there's time. The gun is large enough to make shooting it very comfortable indeed.
The .40S&W HK is my carry gun when I'm not at work / can carry. It's small enough to conceal, potent as a defensive caliber, and has a decent capacity - 12 rounds before reloading. I like that. If I had to draw my gun and defend my life in very close interpersonal combat, I like the controllability of this gun (with a VERY ergonomic grip for my hands and low bore axis) versus the potent round, maybe even more than the SIG in 9mm. The LEM trigger may not be ideal for accuracy work but it's great as a CCW.
The .45ACP 1911 is my nightstand gun. It's heavy, big, long sight radius, and has a limited magazine capacity of awesome, powerful rounds. The SAO trigger is the best of any handgun I have, making rapid, accurate shooting the very best. For answering a crashing down front door - or fighting my way to the shotgun or rifle - I think it's tops.
So I like the .40S&W. It provides variety. It fits a very nice niche in my spectrum of defensive weapons. Plus, if the world ends, I've got a handgun in one of the most popular US calibers, which some may feel is important. Heck, I've got a gun in the 3 most popular US autoloader calibers, even better!
The .45ACP will always be loved because of the 1911. The 9mm will always be loved (by some at least) because of price and capacity. For those interested in diversity or compromise, the .40S&W fills a definite niche.
Also, regarding costs, I find that, if you reload, they really don't cost that much different at all - just a few cents difference for bullets, and the powder and primers are virtually the same, if you've already got the brass