I used .40 for many years in LE work, just as I have used the .45 and 9mm. Of the 3, the .40 has over time become my least favored. It looks great on paper.......good capacity, bigger hole than 9mm, and excellent barrier penetration. As others have stated though, it is hard on guns over time, I find it to be the least accurate of the 3 calibers, its recoil impulse causes more recoil anticipation, and its recoil impulse keeps you off target longer reducing the speed and accuracy of followup shots.
The .40S&W was a good alternative 25 years ago when ammo technology made the 9mm impotent, but with modern 9mm loads equaling the terminal effects performance of .40 loads there isn't enough incentive for me to go back to .40. I'd rather go back to .45acp than go back to .40.