I live in SW Montana where I am likely to encounter either species of bear if I happen to see one. I have a 5 1/2" Redhawk. It stays home most of the time since I bought a 4" Model 69. If you are dealing with coastal brown bears take a shotgun. If you are in the lower 48 you're fine with what you have.
If I had a 29-3 I would consider leaving it home and getting another but I am at the age where I consider it would be difficult to replace that kind of quality. I also would not want the wear and tear that would go with fishing in streams where you are apt to see something close.
Yes, I have heard the grizzlies in Montana are being spotted further and further south. No grizzlies in Colorado since 1979, I would be surprised but not totally shocked to see a reported sighting there within the next few years. Not saying they will get a foothold, but a couple finding their way that far south is a possibility. Majestic animals they are.