I spent two summers camped out in Alaska and never had a bear problem. Rule one, have a decent dog. I brought my Australian Shepard and he was great. We encountered many a bear but the bears would always smell the perimeter Kodi pied around our camps and detour around them. Just in case, I carried a 12 gauge, 6-shot with a pistal grip and 18.5" barrel. First round would be 00 buck and after that I would have 3" magnum, 650grain slugs. A large mass, traveling slower will do a lot more to stop a bear then a high speed bullet that is small. Realistically, you can expect to get off one or two shots. You better hit and do enough damage for it to count. This is where a good bear dog will help you as it will occupy the bears time. Kodi was smart enough to not engage the bear, just stay in-between us and the bear and let the bear know he meant business. Every bear we encountered would back off and leave. I was glad to have my shotgun, but I was prouder of Kodi for keeping me from having to fire a single shot!
44 magnum was the handgun of every guide and mountain man up there. But unless you practice a lot with it, most people will not be able to hit the side of a barn with one. That makes it unsuitable for the casual user. If I was concerned about space, I would opt to take my .357 magnum, but I still think I would take the Mossberg if I was concerned about bears. It is still a handful to shoot, I would not let my wife shoot it, but any burly armed kayaker or rafter can handle it's kick!
But give me a sheep dog anyday!