Call me a coward (I am), but if I decided that I really wanted to hunt grumbly bears I would not be using a .30-06. Oh sure, if that's all I had, blah blah, blah, sure. But given the choice, and lots of time in advance, I would be carrying a hell of a lot more gun.
Most of you know I have played with most of the big boomers. I think my comfort level for big nasty critters would be at 8 mm Rem Mag/.338 Rem Mag and up to about .378 Wby. Above that I am not man enough to hang on to the gun. Or to be more precise, to hold on to a rifle in a weight I could hunt with. 762nato's rifle in .416 Rigby was manageable, but it also weighed about 12 pounds and I do not have a gun-bearer to carry the bloody thing!
Even a .300 Win Mag, which is a lot more gun than a .30-06 in the same calibre, would be too small for my comfort zone.
Doug