I have some 1" grosgrain that I can't break with my hands. The tensile strength is probably greater than 150 lbs. On this pack I'll be using a lot of 3/4" grosgrain, and I only plan to use webbing in two places, at the major load bearing connection between the lower ends of the straps and the bottom of the pack.
My current running pack is an Ultimate Direction Wasp, and I'm attempting to make a pack that is roughly the same weight but bigger (about 1400 cu in., for overnights and weekends). It is a high and narrow race-vest-style pack with big mesh pockets on the front of the straps and no hipbelt. I hope to control bounce with a profusion of grosgrain cinching straps (under the arms, around the pack, etc.) and two sternum straps. The grosgrain will be attached to the pack via hard plastic "loops", so they can be easily cut away and replaced if they wear out due to abrasion against adjustment hardware.