I'm looking for something that's fuel proof and light yet strong for a line on ARF's I'm developing. So, I would say ease of application would be a factor as well as cost. It seems the large "wing skin" balsa sheets I have found are of low quality/density, and obichi ply is heavy and expensive also. Then, I also have to cover them with monocote. Vac bagging the wings was my first preference, as I'm vac bagging the fiberglass fuselages. Brown paper won't cut it as I want to produce a 1st class kit!