I agree that a 7 year contest is going to produce a significantly better end product, but I am not sure where the curve of interest starts to die off. How many other contests have we had that are over 5 years, or is there a way to start with slightly older materials? (it seems harder to start with older materials, if the point is to bend and twist them young, IMO)
I am happy to be part of organizing a X year juniper shohin contest. It think we should start with rooted cuttings, so we take away the issues associated with getting cuttings to take and root well. So I think it should be "established cuttings that are smaller than a pencil" as the starting point.
They are fairly easy to produce, or there are retailers that have materials available.
Am I excluded from participating as a professional grower?

It does not seem that contests have made that sort of exclusion in the past, but I am happy to step aside or participate on the side as an organizer.
John