I bought a set of the Cab's rain suede 2 years ago. Stuff is terrible. I wore it 3 times in the rain and 3 times I got soaked. It sucks up the water like a sponge and it ends up weighing a ton. I honestly think that you would get wet in the stuff if the humidity was high--yeah it's that bad.
Because of my experience with it, I won't ever buy anything made with "dry plus."