The Reflective Lifeline from Hunter Safety System makes so much sense once you actually start using it, and the element of safety it adds to treestand hunting really is worth the minor cost.
This is a simple yet effective product, and it ensures safety before you take the first step off the ground.
I had never considered using a lifeline for hunting from a treestand, but it's so easy. The carabiner clips to your harness before you leave the ground and remains attached as you move up and down the ladder and while you're on the stand. You unclip it when you are back on the ground either to retrieve your animal or head home. The rope provides such a positive system when used with the harness, that it is one of those corners that should never be cut. Don't even consider hunting from a treestand without one.
About the only thing that I found that didn't really hold up was the rubber cover, which keeps the carabiner quiet. The bears seem to enjoy chewing on the covers and leaving the torn shell on the ground at the base of your tree.