I just ran the Spartan Ultra Beast, a 26 mile obstacle/mud race in Vermont with this bag on 9/22/2012, and it did an amazing job! I literally dragged this bag through mud, over rocks, and under barbed wire, fell on it, crawled, rolled, swam, climbed, and it doesnt have a scratch on it. Some slight staining of the mud but that is pretty much it. Its reliable, tough, the bladder doesnt shake around, and all the weight rests on your hips and not on your back. This bag will be coming with me to all my races!