Early conversions of 9mm pistols to 40S&W often resulted in pistols less satisfactory than the original model.
It's something to note that despite the power a 40 has it seems less interesting than 9mm or 45acp to many (including me). A full-size pistol, say, a CZ-75, does nothing for me in 40 but catches my eye in 40. Ditto for a similar pistol in 45acp such as a Springfield Armory P9.
I have owned many 40's, and currently have an uncommon CZ-85 compact in 40S&W, but for some reason I don't go there often. I know there are fans of the 40, but it does seem to run a distant third to the others. Evidently distant enough that FN dropped it altogether (and apparently in non-military caliber civilian law nations, it never got big either).