The market will decide what the class becomes.

My opinion is that it will not be everything to everyone, it will not be a small performance cat for small adults and a performance kids cat.

The small performance cat for small adults is a bloody tiny niche market if you ask me, and already has the hobie wave vying for those dollars and sailors. The performance kids cat is a currently untapped and potentially significant market, not only for business but also for introducing kids to sailing in general and cat sailing specifically.

You should build the DS12 and let your kid decide if she likes sailing. It is a worthwhile experience building a boat. Plus I see some strong movement in the class so I doubt you'll have a worthless boat at the end of it. Heck, build a Tabby if you want a boat that'll carry a bit more weight.

Regarding design issues, design it, promote it, put something specific on paper/on computer. There is a lot of leeway in the F12 concept, even for a small performance cat for small adults. The Tabby was designed on the cusp of the two weight ranges, not for this reason though, I just like the idea of a very full hullshape on cats.