Fazua support is very good , if you are in warranty. But unfortunately bits have to go back to Germany. There are no spares for bottom bracket etc. Where as Bosch do a service kit for their motors.
As you said Fazua are well protected from Ingress but I still put a small amount of innertube between motor and bottom bracket. Though I still do not use it in wet weather.
If you lucky enough to have a Focus Paralane (like me) you get mudguards as well for free.