Simon,
It all depends on the design of both the wings and the hulls. Also how the wings attach and pivot to fold up.

While I agree with many of your points I think there is a fair chance the right design could solve or significanlty minimise the possible drawbacks.

I think a well designed 20ft winged boat would have the convenience of a smaller beamed boat yet should also be a more comfortable, more exciting and therefore more enjoyable boat to sail.

The way I see it, you never really know until you give it a go.

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!