Not that my opinion or experience means much but....

Either round is good. Most people find the recoil of a .40 S&W to be a little sharp but recoil is pretty much a preceived force.

I like the .45acp and have been carrying a 1911 for several years in work. Not once have I seen anyone hit with a .45 or .40 continue aggression. I have seen more one shot fatals from .45acp but I have seen more shot by .40 S&W.

As stated by another poster, the shootee will not be able to say what caliber he was hit by. Nor can he say how fast the bullet was travelling. If he is able to say anything, it will be asking for medical attention.

I appreciate the fact that you have an interest in those two calibers as opposed to smaller calibers.