Yeah, it seems like the stopping power debate will never end. My logic tells me that even though people have been stopped at one time or another with everything ever fired in every caliber known, I depend on big bullets making big holes. Two .45's are going to have a better chance, no matter how small, of hitting or knicking something vital than two of any smaller caliber.
Draw an imaginary line between your nipples, and center a 4 inch circle on it over your sternum. Into that circle I would rather put a .45acp slug than a 9mm slug. Now then, I know the 9mm's may do just as much damage but I'd prefer staking my life on the .45's... IMNSHO.