do.
9mm is seeing a resurgence among police and LE. Bullet design has really helped to close the gap.
Two major points should be made, and I already have made them but for emphasis, I will again.
Shot placement is king. Shooting someone in the pinky probably won't stop a determined attacker. Since I pay for my own ammo, the cheaper 9mm means I can practice more and means I will be more likely to hit my target. Not to mention extra rounds, softer shooting, means more accurate and fast follow up shots.
Handguns suck in a fight. They are harder to be accurate with and they are much less powerful than a rifle. In fact, stats show that 66% of people shot with a rifle die and only 33% of people shot with a pistol die. The power difference between a 9mm and a .45 is much less than many people would like to think.
Lastly, if you are ever in a gun fight, there is no such thing as a magical one shot stop. Shoot the threat until the threat no longer exists.