Well i dont have near the time in the backcountry as you WD. I did have a failure 3 years ago. Lost zipper stop on bottom of my thirty year old Snow lion Bag. Result was zipper popped open at night. Thought I would freeze. Next morning I was able to line zipper back up ,and sew shut at bottom to replace stop. It got me threw the rest of the trip! Good thing too cause final night droped to 17 degrees and high winds. I was in leconte shelter. With all my clothes on I stayed comfy! I always have a needle and thread in first aid bag.