I am another who would not consider the .40 S&W a flop. I liked the .40, until my hands aged-out of shooting it through high-bore-axis, light-alloy-frame pistols. That was when I reached age 50, in 2011. Step one was to resume using a 1911 as a personal-time carry weapon, a departure from my usual habit of using only one auto-pistol system at a time, for both primary duty and primary personal carry. (That steel frame damps recoil, the bore axis of a 1911 is low, and .45 ACP accelerates more gently.) As soon as my chief authorized 9mm to be an alternative duty cartridge, in the 9mm versions of the already-approved duty pistols, in 2015, I switched to a Gen4 Glock 17 duty pistol.
It is not that .40 S&W had wrecked my right thumb, hand, and wrist, on its own. Big-bore Magnums, in the Eighties, probably did most of the damage. Had I trained less often, with .44 and then .41 Mags, I might have been able to continue using .40 S&W. I still have my SIG P229R DAK .40 duty pistol; honorably retired from carry status, my longest-serving individual duty pistol, for eleven of my 33+ years of service. I sold or traded my other .40 pistols.