One aspect I did not mention which is the reason one should try them, is the ability to apply more torque to the crank arm when the leg is in the best position to generate force. One can adjust the Rotor Q rings to exactly where one can apply the most torque. It is similar to having a cam on the weight machines in the gym to match the degree of difficulty to muscular capability. This sounds so right, it has to work.
Unless it does not.