I picture a bear attack going something like this... You hear a noise, look in the direction of the noise, and see an incredibly fast animal charging at you from a close distance. You pull out whatever gun you have and fire as many shots as you can in about 2 seconds.
Ive shot a 500mag, and I own and shoot regularly both 44mag, and 45 acp. Given the above scenario, I believe I could put more bullets on target with my 1911 than a magnum revolver. Now what those rounds will actually do, I have no idea and quite frankly neither does anyone else here.
I'd take my 44 if I had a choice, but I wouldn't let carrying a 45acp stop me. If you're in an area where the difference between a 45acp and 44mag is the difference between death or life..... GO SOMEWHERE ELSE!
There are many things in life that are out of my control. Recoil isn't one of them.