In use the 9mm has beyond a shadow of a doubt proven that it is ineffective of stopping the enemy. The .45 has proven that it is effective.
The 9mm is a favorite of gangstas and punks because it is available in smaller framed models and more concealable. There is a reason that the FBI and front line troops have gone back to the .45. It works. The 9 doesnt.
My EDC is an STI Trojan with modifications. My throw away is a Llama that I bought off the street for $85. Either one of these will put 20 in the black at 20 yards in 15 seconds. When there is a standard on the street, it doesnt make sense to attempt to lower it.