The may I understand automatic slats to work operation is dependent on the leading edge stagnation point moving down from the leading edge to the lower surface as the angle of attack increases. When it hits the right spot the airpressure actually forces the slat open rather than the spring pressure. Hence Paul's experience with slats that move by light finger pressure. As I recall my reading the pilots could hear the slats bang back and forth in tight combat as the turns tightened and the angles of attack reached the trip point regardless of airspeed. Making automatic slats that work with RC sized models would be a sensitive watchmaker like project. Servo operated leading edge slats would be far better. At least that way they will both operate at the same time.

My own feeling is that this is an area where there just is not enough wing tunnel work at the sizes and Reynolds numbers we work at. So for my own efforts I'd use flaps in an instant but forget the slats.