Re: grizzly defence question
Seeing as though I was the guy who posted the Moose incident with spray yesterday, I'll chime in.
I think SofaKing was spot on about commenting on your confidence level given you're already questioning the .308. For that very reason I would take your shotgun loaded with 3 inch slugs. The added weight will be far surpassed by your added sense of confidence, and the extra enjoyment you'll get out of your trip as you won't be looking over your shoulder the entire time. Although, checking your surroundings often is still a smart thing to do.
That being said, and with no experience to back this up...my gut instinct tells me the best strategy would be spray first, and IF you get the chance and are still in imminent danger, shoot to kill second. I just can't see a bear dying quickly enough to stop a potential deadly attack from gunshots, whereas I can see a bear becoming blind or incapacitated by spray almost instantly.
What goes around, comes around. Think first, and always act with respect.