We commonly get the question regarding the relationship between Speed controller switching frequency and the linear or nonlinear output of a speed controller. Switching frequency has a very minor effect on the output linearity.
PWM time period is linear with respect to output duty cycle ,but not linear with output power. The reason our victor and motor controller 29 have nonlinear outputs is that our firmware in those micro controllers did not account for this nonlinear relationship. Newer versions of these controllers will have linear output power vs PWM input when we change the firmware for the next processor production run.