Personally, I don't generally argue with the .45 guys. There is a good enough ballistic difference between the 2 to say the .45 is "better". It's the .40 guys who just crack me up. I start by telling them the evolution of the round, then I let them know that I've actually done some research and looked at the numbers, and I finish it off by telling them there is zero ballistic difference between a 9mm and .40. Why take more recoil and lower capacity if all else is equal (it is..)
But, like you, I've seen several people shot with several different calibers. Shot placement and luck always proves to be the most important factor.