It's one more thing to take with me. It sorta restricts my movement.
Your movement will be much more restricted when you're a para/quadrapelegic.
I used to use just a safety belt, now it's a safety harness. I'd feel naked and vulnerable up a tree without it. I've never needed to rely on it, but some of my hunting friends have. Using it for a while will get you used to how to make it most effective without restricting you too much.