What I was saying about the .375 H&H was to make a point about bullet placement - a handier rifle capable of making a head shot would be preferable to a large rifle that couldn't.
I won't speculate about black bears but a handgun on a brown or grizzly is.. well, I won't say its useless, but its a poor choice.
When a bear attacks its already adrenalized. Shots to the body aren't going to kill it before it gets you. Whats needed is something light, handy and accurate enough to bust the bears brain pan. Horsepower is good but accuracy and quick handling are far more important.
The other consideration is this - picture yourself with a daypack, a couple of fishing rods, lunch, survival gear (in Alaska you always prepare to spend the night), lures, flies, fishing tackle, water (beer) - see what I mean? You drop a heavy rifle on top of all that and you aren't going to get it up in time.
The Marlin Guide gun is still a pretty hefty piece of hardware. The C0-Pilot conversion is expensive but it does make the rifle more suitable for that scenario - I want one but its big bucks and will have to wait.
It hard to explain to people who haven't been there but bear attacks are FAST. When I got hit the bear was about fifteen yards off, lying in the brush. It sprang and I reacted immediately by raisng my rifle - it was on me before my rifle reached my shoulder. Bears in attack mode move like big cats, like 1500 pound tigers, a big caliber won't save you but a head shot (if you're quick enough) just might. Thats my frame of reference. I've been there.
The Bears and Bear Maulings Page: members.xoom.com/keithrogan