Carl,
At this stage I don't have a preference.

I'd like to think that I could work towards developing a single set of plans with options in the instructions that will allow people to build in their preferred material from the following selection :-
1) ply/glass
2) foam sandwich (using a combination of glass or carbon and kevlar
3)cedar with glass or carbon.

While you may be able to build to various weights using these different methods the plans should provide specs that will bring all 3 into a weight range difference of no more than a few kilos. I think on a 20ft boat with a spinnaker this should not have a huge impact on performance.

As to my question- I was just curious as to which material you would be most likely to select if you were to build a 20ft cat.

Regards,
Phill

I know that the voices in my head aint real,
but they have some pretty good ideas.
There is no such thing as a quick fix and I've never had free lunch!