I find expo to be very useful, even for the beginner as he has less tendency to overcontrol. A couple of the comments above appear to have the writer thinking about dual rates or end-travel-adjustment rather than expo. The nice thing about expo is that you can get very precise control with low stick movement yet get max throw when needed by just moving the sticks a bit more. It is especially helpful on rudder when learning to fly a tail dragger as it keeps the student from overcontrolling.