mr.frosty: Well, here's my opinion: the 45 is better for personal defense simply because it throws a fatter, heavier chunk of stuff that has the tendency to wallop the absolute schmidt out of whoever it hits. I have used plain mil-spec ball ammo in all my encounters because it worked so well and I continue to use plain ball. The only improvement I feel I could realistically make over the plain ball design is to make it a non-expanding semi-wadcutter and shoot it at the same velocity.
When it comes to the 45 for defense and considering the slower velocities of the 45 I believe you can only trust a non-expanding bullet not to expand, but you cannot trust a hollow-point or soft nose to expand. I expect the heavier caliber with a hard cast or full metal jacket non-expanding semi-wadcutter to do just that - not expand. That meets the standard of performance I have come to expect from the 45, both in combat and personal defense.
The 10mm/40 bore however is one of my favorites, and Lloyd is absolutely correct about its power levels. It is an excellent whitetail/black bear choice in the conventional size/style semi-auto. The 10mm can be loaded with a variety of bullet styles shared by the 38-40 which includes a Keith style semi-wadcutter design and a round nosed flat point designed for a lever action and I believe there is an older Lyman 195 gn swc as well. The 10mm is at the lighter end of 41 magnum loads and is heavier than the 357, I feel. Either cartridge will do the job at 50-100 yds (depending on many things) but your 1911 sights might limit you more than the cartridges capability.
I would consider loading the 10mm down to 40 S&W levels for personal defense. The 10mm will clearly shoot through a human torso, or a house, most likely the neighbor's cow, definately a whitetail or black bear, and probably a 57 Chevy, so ya might want to slow it down a bit for personal defense so as not to eliminate the rest of the neighborhood with the first t&t. Again, I would not trust a bullet to do what is advertised unless it is a non-expanding design.
HTH. Mikey.