I stand corrected on the pressure thing, but a .45ACP+P is still WAY more performance than anything you can eek out of a .40 due to the .40 operating, by design, at max. The .40 is not going to equal or replace the .45. It is just a fine little thing in the middle for those who don't need or or think they can handle the .45. Makes them feel warmer and fuzzier than toting a 9mm.
I have to disagree. I love the .45 and shoot it often, but if you want to eek more out of the .45 than a .40, you have to go up to a .45 Super. It's essentially a .45 ACP +P+, and can be loaded to 30K+ PSI. I load for it, and from a 5" bbl it can shoot 230gr JHP @ 1200+ fps and 200gr JHP @ 1350+ fps and 255gr hardcasts at 1150 fps.
However, the .40 can manage more than the .45 ACP/ACP +P can. While the .45 has a larger case and could hold more powder, it's lower pressure which hurts it when compared to the .40. I don't know where people get that the .40 is always somehow operating at max, that's not true. Even factory loads for 165gr can vary 200 fps, so I suppose both are "max"? Most would agree that between the three, the .40 recoils more than both the 9mm and .45, so the whole "can't handle a .45 so they shoot a .40" thing makes zero sense. It's easier to handle a .45 than it is a .40, so I guess .45 guys carry one because they can't handle the .40?
I handload for everything, and from a 5" bbl, I've shot 230gr .45's at 1000 fps with no issue using Power Pistol. But with factory loads, I know that while most 185gr +P .45 loads claim 1150 fps, they're usually doing less than 1100 fps, and just over 1000 fps from a 3.78" Glock 30 bbl. It's no problem to get a 180gr @ 1200 fps from a 4" .40 S&W, and in excess of 1300 fps from a 6" bbl. With the right powders and from a 4" barrel the .40 will shoot a 135gr over 1500 fps, 155gr at 1400 fps, 165gr over 1300 fps and 200gr over 1100 fps, throw in a longer barrel and it only gets faster.
Calling the .40 sissy is silly. I know this will go over about as well as fart in church, but the .40 is capable of MORE than the .45 ACP/ACP +P.