Hi Fred,
The Magic Pie is equipped with Hall Sensors, so it can be used with either sensor controlled or sensorless brushless motor controllers.
The Magic Pie's controller usually works in sensor controlled mode, but will automatically switch to sensorless mode if one or more of the sensors fail.
It should therefore possible to use the Pie's controller with other direct drive brushless hubmotors, whether they are equipped with Hall Sensors or not.
The biggest problem with operating the GM controller in sensorless mode is that the motors don't usually start on their own when the throttle is operated, so they need to be turning before the throttle will work.
This unfortunately prevents the GM controllers from working with geared motors that contain a unidirectional clutch mechanism (an internal freewheel device that prevents the wheel from turning the motor, virtually eliminating all of the mechanical and magnetic drag from the gears and motor while coasting or pedalling without motor assistance).
Some of the more recent sensorless controllers are able to start the motor from stationary, but I don't think the majority of sensorless controllers are able to do this. Also, some sensorless controllers don't work very well with high rpm geared motors.
Alan
