Wow, what a thread!
I'm am in the middle of this debate myself.
It sure seems to me that there are 2 different debates going on here: 1) panic self-defense situations, and 2) a kill/drop shot for game.
Everyone here is making great points, and I have enjoyed reading/learning from this thread.
My JOB is panic situations (fireman), but I have never had to shoot in a panic situation. I have only been to Alaska once, and that was a fishing trip. I chose to take the 1911 for a sidearm against a bear if needed. To me, that seemed undergunned, but that's what I was most familiar with, and felt I could put as many rounds as I could in a panic situation. So that logic won out. Fortunately, for us and the local bears, we didn't need them.
In N/A, Moose, Bears and buffalo seem to me to be the largest of the game we have, right? Am I missing any?
When you are hunting to survive, you're getting A LOT of practice, and you use what you have - I know a guy that used a 22lr to harvest elk to survive by shooting them in the eye (he was alone on a wilderness farm many years ago) You use what you have.
If you're hunting by choice (sport), I believe it's proper and responsible to 'use enough gun'. I've used a 30-30 lever gun hunting elk before. Why, it had open sights and the terrain I was in meant any shot I might get was within 40 yards, and dense brush. So, to me, that wasn't irresponsible.
I have read before that most AK residents in the rural areas rarely use anything larger than the .308 or 30-06. Don't know for sure, but I've read that before on more than one occasion. Well, if you're harvesting several critters a year, and you have all kinds of time to practice shot placement and the effects of different shots, then great. But, if you're an occasional hunter, who logs a responsible amount of range time with their gun prior to a hunt, and picks ONE gun, perhaps it's not unwise to select one with a little more energy. Especially when you consider the range you may be presented with when you encounter your chosen game.
Here's an example: can you go get a load of gravel in a pickup truck? yup. would it be easier to have a dump bed on that pickup truck? uh huh.
So, I see a lot of folks here who love that 30-06. That's a darn fine round. Very versatile, and proven. But, for the occasional hunter, as most folks are, (I would suggest one critter or less/year = occasional) perhaps a bit larger gun might be a wise choice, especially if you don't have a hunting rifle already.
Yeah, Finn Aaguard (sp?) shot everything on the African Continent with a 7x57. Great for him. I'm not Finn Aaguard. I'm not a professional big game hunter. So if I'm gonna go after dangerous game (I'd argue that bear and moose qualify as dangerous game), I think I'd rather have a bigger gun. Especially since they are available.
That .308 is a darn fine round to punch paper with out to, and past 1000 yards, as many have argued. But, if I'm going to go to AK or Canada after moose, I think I'd rather have the extra energy that a Magnum cartridge can offer (more energy at longer distances) in case my skills aren't as spot on perfect as the locals who harvest several critters each year.
I don't think anyone should go hunting without being responsibly familiar with their hunting gun(s). That being said, a little larger gun might make up for some human errors we all might (and will make) when we take our shots.
To answer the OP, I think it's asking a lot to try and do it all with one gun. Would it be a good idea go have two, with a little 'overlap' in the middle. And, we can always home-load to cater our loads according to our game.
I think I've decided on what my smaller gun will be: .308 for Mulees and smaller, now I need to figure out what my larger one will be for elk and larger.