The conduit is wider than the rope distributing th eclimber's weight over a larger surface area and the saver is not moving as much after installation so the impact on the tree is much less than just using the rope alone with all the friction and dragging over the branch.
I do not think that the fact that the friction saver has an internal _meta_l jacket makes more impact on the branch as a matter of fact what is in contact with the branch is the softer outer coat of plastic that is rather soft. IMHO
