In my own personal experiance with carbon fiber vs. aluminum, you are not going to lose a bunch of weight. Aluminum alloys we use are very close to the weight of carbon fiber and are much cheaper, easier to work with and easier to fix. We can match the weight of carbon fiber on some applications by drilling out non-load bearing sections and butting others.

H-18 wings are pretty light to begin with. I don't see the performance advantage in using carbon fiber in this application.