[MetalMan]

Sensored motors have sensors on them that tell the controller where the rotor is. This makes it so that power can be applied very rapidly. With sensorless, the controller detects the rotor position by EMF from the motor. At a low throttle input, it is much harder for the controller to detect where the rotor is, and can lead to "cogging".

If you go with a XL motor with a high kv (4200 or 5000), make sure to get some batteries and a controller that can handle a lot of amps. Those motors are more than capable of burning out some batteries that aren't up to the task.