The bonus with Dyneema/Spectra is the abrasion resistance and strength for its weight. The stuff is remarkable. However, it is also expensive and difficult to color. The Dyneema grid fabric is standard lightweight nylon fabric with Dyneema grids woven in for extra strength and tear resistance.
Dan generally provides a full Spectra bottom standard on his packs. On my pack I added a Dyneema kagaroo pouch on the back as I like to lay my pack down on its back typically. Beyond the bottom and back, I've never had any wear issues with any previous packs so I opted for standard 500d Cordura for the the remainder.
