On my elk hunt in NM, got to talking to a guy who had asked a guide up in MT that same question, regarding grizzlies etc...

he figured a guide would run into a few grizzlies a season, he told us that guides were constantly running into them, that this outfitter had I think 2 guides mauled or charged etc...

I just remember him being surprised by how bad it was...that it was a real problem/chance.

I'd certainly either have a rifle ready, and/or bear spray.