IIRC, the .40 S&W came about because the 10mm was deemed too hot for the FBI. So some reduced charge loads were brewed up amounting to what is now the .40.
I never got excited about it, and after reading about unpleasant recoil impulses etc. decided to just keep on keeping on with the good old .45 ACP. Had a 9mm for decades, but after I sold it, just could not come up with a good reason to get another.
The .40 just seemed like a more unpleasant version of the 9mm, but as I said, never had one, so it might not be so bad. Still, with my .45s, there is no point in it. Just might try a 10mm barrel one of these days just to see what it is like. Lots of guys seem to love the cartridge for hunting.