I only own two semi-auto handguns, and they're both in .45acp, although I'm now pretty convinced that there is little advantage in .45acp over 9mm. Unless you get into the realm of magnums and rifle rounds (where you'd see fragmentation and tumbling), you probably won't notice much of a difference in having an extra 100fps or extra 0.1" diameter wound channel. Either way, if you're going up against someone who's intent on killing you, you're going to need to hit them in a vital organ or CNS to incapacitate them. If you think that displacing just slightly more flesh with the .45 is going to make a difference between life and death, then I'd argue that being able to make a follow-up shot just a tiny bit faster with the 9mm could make that difference as well.
Oh and on a side note, I've got a Glock 35 on the way that I'm gonna convert to .357 SIG. :P
Oh and on a side note, I've got a Glock 35 on the way that I'm gonna convert to .357 SIG. :P