Me and Dad have been down and tried to do to the jumps what you all asked. We have smoothed them off but they still cant be done in the wet(even me). They are not ment to be done in the wet. Regards nose diving, this is because you still need to blip the throttle to pick the nose up.
If you are still not happy we can always race on flat grass and have no jumps so every body can go round easily.
