Maybe, I'm not understanding, but are you suggesting to use your ATC as your attachment to your tether while you're hunting at height? If this is accurate, you are just relying on the friction of the rope against the ATC and carabiners to hold you in place. The way you show it in your pic, you are effectively already in "rappelling mode" . If you slipped, you'd be relying on your prusik below it to actually stop you from sliding all the way down the rope. I see this a potentially serious problem if you were trying to get around the tree for a shot. IF you shifted your weight wrong, you could easily overcome the friction and start sliding down your tether until your prusik caught. If you are relying on the autoblock feature, my understanding is that this isn't really what it was designed for. The autoblock is designed to be used when belaying a climber, and it's really a failsafe, should your attention wander or something else cause you to let go of the rope. I don't believe it's intended to be relied upon exclusively. Plus, if you are moving around, you'd be weighting and unweighting your tether slightly, which could cause the autoblock to disengage. My apologies if I'm misunderstanding what you are suggesting.