I've toured tons in very mountainous terrain with, for me, a heavy load, 50, 60lbs at times, on 160mm rotors on avid bb7 and all was fine
BUT you have to realize that braking technique is the factor here that makes or breaks your question.
And I only weigh 135-140
Thanks for the input. Is the technique to avoid "dragging" the brakes for long periods and allowing heat build-up?