I have this system installed in my RV and can tell you it works great.

The airspeed is determined by a switch installed in the pitot line. You also have adjustments for the actuator speed in both the high/low airspeed ranges. Finally in the event of a run away trim motor the system limits engagement to about three seconds, the you can use the panel switch to reverse the actuator, relieving the control pressures, then disable the system for flight until landing can be completed.

The guys at TCW are great to work with, so don't hesitate to call with questions about there systems.