givens, I went through the same thing. I ended up with an XD9 over an XD40 for these reasons:
1) The XD9 is about 30-40% cheaper on ammo (WWB and other ammo you buy at places like Wal-mart and Bass Pro)
2) My wife likes the 9mm for the lower recoil.
3) I can shoot more because the ammo's cheaper.
4) I love irritating Sarah Brady by packing 15+1 rounds of ammo. :twisted:
5) Like a 45 relative to a 40, the only advantage to the 40 over the 9mm is a bigger bullet. In that 1-in-a-million (OK, slight exaggeration since I live in the Memphis area) chance that I'd ever have to use it for self-defense, there's only a 1-in-a-million chance that a 9mm would fail to do the job that a 40 would do. Anyway, I think you'd be better off concerning yourself with other things - like not playing golf in a thunderstorm or such.
I'm going to get a 1911 .45 (Springfield GI or Mil-Spec model) at some point before long, but it's not because I worry about "stopping power".
I've got the service model. I'd like to pick up a sub-compact. Probably look for one in .40 just to have some variety in life, but I'll gladly snap up one in 9mm --- probably from some guy who read one too many message boards and thinks if he shoots someone with a 9mm, "it's only gonna make them mad". Local gun range had one for $350 with 2 mags, but I don't have the money for it right now

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