My thought was that any grit which gets into one of these shoes and works its way under the footbed will almost certainly puncture the membrane, since the weight of the wearer will be pressing down on it. Also, not much good for those who use replacement footbeds.
All the windshirts I've used have started to feel clammy when I worked hard enough, but the least prone to this was a single layer cotton ventile top I got from the old Survival Aids shop in Morland. It really was streets ahead of all the synthetic tops I've used in this respect, and turned a decent shower when proofed with the stuff Survival Aids also sold. The downsides were its comparatively high weight and packed bulk, plus the fact it took ages to dry when it did wet out.