I didn't vote, because in my opinion it is about usability more than power factor. I'm a full believer in the most powerful that you can comfortably shoot and carry comfortably. If all you can handle and conceal is a .22lr that is better than nothing and better than something too big for you. If you can shoot a 9 mm it has the power to make someone either dead or at least change their minds. If you can shoot a .45 acp it will not only do massive damage, but it will knock them over if you at least hit mass. And, a .40 has darn near the same balistics as a .45 acp in the range we talk about for self defence ... speaking of which ...
Badger ... what are you doing quoting 100 yard ballistics in a self defense situation. Self defense is typically a 25 foot radius, and 100 yards is predator ... you're the predator!
Test ergonomics, concealability and comfort. Beyond that there is no such thing as too big or too small.