Grandad, there are some interesting points made here and I do not disagree with them. However, i do not believe that the POH catagorically says that 10º flaps should not be used, it merely states no precise data for that setting.
If 10º should never be used for take off and provides no advantage for landing then all it serves to do is act as a stepping stone to get to 25º.
Surely, like Cough says, 10º provides a better view particularly if you are trying to hold off the nose wheel on a grass strip. in this case you don't end up doing the last 200 meters of the take off run with much reduced vis.