I built one of Gentry's Chucknut 12's for my 11 year old daughter last year and it works well for her. I also just completed a PBK 27 Sea Scout (13') for my wife, but my kids now 10 and 12 spent a good part of a week paddling both of these boats with relative ease conditions like you mention. I especially like that they can paddle them now and as they grow. Comparing the boats I found the C12 is a little easier to build. For the PBK I kept the lines the same but modified the construction details and built it with lashed epoxy joints a-la Yost, Horten, and Gentry. The PBK has less initial stability and seems a little faster but as far as overall handling they are pretty similar to each other. The PBK does have a lower freeboard and bow which might be an advantage on a windy lake. I'm planning on building another C12 next for my 10 year old and then possibly a 14' or 15' PBK for myself.

Here's links to photos of my builds..
http://flic.kr/s/aHsjyw4R38
http://flic.kr/s/aHsju6Krge

- Don