Picking the fight will be safer than finishing the fight.......... Shooting an unsuspecting critter vs one with the adrenaline already up is a perspective changer. Never had to stop a grizzly charge but I'll place my experience with raccons and Badgers on this one. They ain't hard to kill with a .22 if they don't know what's about to happen, but if they're already mad/scared, .38 hollow points ain't enough short of a head shot, my kids and pets can tell ya all about it.
If Mr bear is just out fishing with his buddies, I'd be ok with a bonded or better loaded .243, if he's out to ascertain his place over me in the food chain, I'd like a .458 soccom I think.
That being said, I find no fault with the .243/30-06 combo, not my personal preference, but close enough not to argue about it. I'd concede folks on the point of a .223, or .280, or 7 RM, or .375, or .45-70, thankfully we're still allowed to make those choices for ourselves (unless an outfitter says otherwise)....