Dyneema (also called Cuben Fiber) is an ultra-light laminate material that offers the best strength-to-weight ratio of any pack fabric. If you're counting every gram for ski mountaineering races or fast-and-light touring, it's a legitimate game-changer—you'll feel the difference on long ascents.
However, there are real trade-offs. Dyneema has less abrasion resistance than heavy nylon, so ski edges and rocky surfaces can damage it more easily. It's also not field-repairable like nylon, and the cost is significantly higher.
For most backcountry skiers, midweight nylon (200–400D) is the smarter choice—it handles ski edges and normal wear without the premium price tag. Dyneema is best for experienced tourers who are meticulous about gear care and prioritize weight above all else.