i have a fairly new Hill that has a flat shelf. One of the points raised by Learner that is interesting to me is the effect of a flat shelf on nock point height. With a radiused shelf, as you raise the nock point, you incrementally move the contact point forward on the shelf. With a flat shelf, the contact point is either flat on the shelf or on the back or front edge of the shelf, depending on the height of the nock point. Ideally, the contact point would be directly above the pressure point on the grip, which for an ASL would be near the back edge of the shelf. Since I shoot 3 under, which generally requires a higher nock point, my contact point is on the front edge of the shelf pad. I suppose this might be another reason why you shouldn't shoot an ASL 3 under, but I'm not going to change my whole style of shooting for one bow that I don't shoot that often anyway. Hill shelfs are fairly narrow front to back, so maybe the difference between the arrow resting on the front or back edge of the shelf isn't that significant, but I would imagine that on some recurves, where the shelf might be several inches long, it would be better to have a radiused shelf so there wouldn't be such a dramatic change when the contact point shifts. Or, as was suggested, just put something under the shelf rest where you want the contact point to be.