Dave, it is essential to have a small deadband on speedos, some may have too much (standard 4QDs) and some are adjustable (Vantec & Roboteq). The wider the deadband the less stick movement you have left to control the power. Too small a deadband and the robot may creep due to tolerances in the transmitter / receiver and speedo. Effectively, within the deadband, stick movement has no affect on the power to the motor. Not sure I understand what Aaron is referring to.

More advanced speedos also allow you to adjust the relationship between stick position and power to the motor. Most basic speedos are a linear response. Again, more advanced speedos allow an exponential to logarithmic relationship.

Paul