Amen to that.... the chances of encountering the many other varieties of "annoying" animals and humans are much greater than encountering a bear in most cases. Up here I'm more worried about a pissed off moose or pack of wolves than I am of a bear.
The 10mm is adequate to stop anything you shoot right; McNett has done tests with his HCFN gas checked loads and found that they do about 24 1x4 pieces of pine in a baffle box out of a stock Glock barrel. The Glock is my first choice for most places as I value capacity with adequate power over 5-6 rounds with 1.5-2x the power. When I'm in the Black Hills or the Big Horns my G20 is on my hip with hardcasts and a 6" Jarvis barrel.
If you call Double Tap and speak with Mike McNett he'll tell you about some of the photos his customers have sent him... 1000+ lb moose and bison with his 200-230 gr 10mm stuff, and a pig down in Texarkana that was 350 lbs or something... shot right above it's pooper and the bullet exited the chest as was not recovered. In a survival situation or and 90% of the situations I will encounter in the mountains I'll take the 15+1 of adequate over the heavier Redhawk.
If I'm going to be running around in the Tetons for more than a few minutes, I do carry my 44 mag with 320 gr hardcasts at @ 1250 fps. That's the largest gun I care to pack; those SRH and X-frames are so damn big they're unpleasant to carry for long. An adequate gun that stays on your hip is better than a monster that's sitting on the camp table while you're down at the stream!
As far as the bears go.... as some people here have noted it's very rare for a bear encounter to go bad. If that's the case, I would take a .45 over nothing, but the 45 acp does not penetrate well. Penetration is going to be the second factor, right after "can you hit what you're aiming at under stress." If you must carry your 45 at least pick up some hardcast +P stuff so you have a chance.
There are documented occurrences where brown bears have been killed by 9mm and 38 spl. IIRC, the 9mm was a guy who was in the middle of a river and shot the brown that was attacking his friend on the bank.... hit it in the eye or something. The 38 spl was a hiker who fired (blindly) directly into the bear's ear while the critter was on top of him chewing on his other arm. Guy was in the fetal position and reached down and got his piece loose, then killed the bear with a lucky, blind, desperate shot.
There is no sure thing for a bear... other than a vehicle-mounted mini gun I suppose. Your best bet is to know where you're at, pay attention to what's going on around you, and not panic if you see something that may eat you. The gun should be your last-resort.