Getting back to your original questions Richard:
I would say that the first three (breathability, water resistance and weight) are the most important to me. Other factors are nice, and will play a part in my purchasing decision, but those three are by far the most important for me. For example, I care about durability, but own Propore (I just know they are fragile). I want to save money, but I've bought (and will continue to by) Cuben. If there is some magic windshirt that does well in all three categories, then I'll spend lots of money, even if is fragile.
With that in mind, I suggest a table with at least those three items. It can have more (your call). Along with that, I would make a chart with breathability on the X and water resistance on the Y (these can be swapped if you prefer). Then I would represent weight with a bubble (the bigger the bubble, the heavier it is). I think this would be fairly intuitive. For example, if you were displaying rain jackets, than an Event jacket shows up in the upper right quadrant (very breathable and water resistant). A Propore jacket is a little bit closer to the axes. But the Propore jacket has a much smaller circle. (I've used rain jackets for my examples, even though I know this is for comparing windshirts).
The other advantage of this approach is that you can draw a line to designate something. For example, you could have a line designate what is generally considered "waterproof". Beyond that, a lot of people won't care if a jacket is more water resistant. Likewise, a line for the 35 marker on CFM.