the seat that my bows rest on when on the tree is radiused, so the bow only sits on one spot of the curve (generally center of handle). I found this worked better for me than a rest which was flat. Of course, the rounded seat means the bow has to be balanced better than if it were flat before you apply any draw. In all, until the bow is braced, I find I have to use a clamp to hold the bow on the seat when tillering w the long string.
Russ