Roger,
you could start with a theoretical outlay and keep the testing for a later date. I still feel there's a huge gap in knowledge about what repellents are, how they function based on composition or way they are integrated on/in a fabric, why getting durability is a problem, what properties of fibers/yarns/fabric weave influence durability and effectivity, should some (current or future) fabrics offer better performance, … What are these nanorepellents and similar and how do they differ from from standard water repellents and most importantly why shouldn't we exspect them to be any better over time? Environmental concerns or public health are other points of interest. Or care instructions.
May we exspect to see repellents that keep on beading al day long, day after day?
A real comparable test seems pretty difficult to me at this time because some treatments are not available on consumerlevel so you would have to test complete garments and at that point thre are so many variables, it's hard to distinguish what you're testing. And personally, I feel that such a test would show little significant differences between treatments over the midterm or longterm: all inadequate.
