@bill: to be honest, I think noone ran in wet conditions with brushless yet! But apart from a good sealing job on the speedo, there shouldn't be a real problem running the motor in the wet. Maybe you can seal the openings of the motor with some gel, so no water emerges into the motor.
@azmio: I'm actually Swiss, but live and work in Germany since 8 years. But german is my native language.