Ok I'll put my 2 cents in.

The question to be asked is why do we always need to change something that is going ok ?. Do you always have to keep up with the Jones's ?.

As an example look at the Moth class. In the 70's to 80's they were everywhere and they were producing champions galore, in a good class which allowed a fair amount of design variation. The designers went crazy with pencil thin skiffs, the scows became obsolete, the skiffs were harder to sail, numbers plumeted. Innovation or progress as some call it has seen a class be almost destroyed.

I can see the reason behind the MK 1 Mossies to add a spinnaker, but talk it through with everyone to get a good cross section of views. Will the fathead sail really add anything to the class?.

Change for athetics or to keep up with the Jones's is not a very good basis for change.

Mossie's are Mossie's, not Tornadoes or Taipans.