I use the gizmo as I tiller from brace through almost to full draw on difficult staves. If I get the bow to bend well in the early stages of tillering I don't need the gizmo, usually, the rest of the way to full draw.
Beyond a certain point(about brace height), I don't like using a tiller stick. I believe it puts too much unnecessary stress on an uneducated stave. Sometimes I find it necessary but usually I can get a bow to full draw using the tiller stick only for the first few inches, if at all.