I've handled S&W's 500 snubbie in the store, haven't handled the Raging Bull yet.
After handling the S&W and reading the specs on the Taurus, I think the Ruger is the best backcountry pistola for bears. The S&W and Taurus are quite a bit larger and heavier making them more of a pain to carry on hikes and fishing trips. The S&W is a lot more expensive than the Ruger or Taurus(though I'd gladly spend the money if I thought it would save my life). The added power of the 500 would be nice against a large grizzly. Though with those bears its as much important where you hit them as it is what you hit them with. So I think I'll take the extra bullet in the ruger 454 over the extra power of the 500. Plus the ruger is more usefull because you can load it up with 45 colt for home defense as well.
I may be biased since I bought the Ruger before the snubbie 500's were available, but I think these are some valid reasons to stick with the ruger for back country bear protection.
If I ever see a used taurus 500 snubbie for sale at a good price I'd probably get it just to have and shoot. I have more fun shooting my 454 snubbie than any of my other pistols, so I'd love a 500 in my collection.