My individual experience with the U.L. Thermawrap Action Jacket is that an hour-long light rain beaded up nicely, and ran off the fabric without penetrating. The stretchy side-panels breathed as well as cotton T-shirt material. The elastic panels also sucked the garment to the body, minimizing the bellows effect that often pumps precious warm air away. However, the stretch was not so strong as to interfere with my breathing, YMMV. The forearms were not as breathable as I liked, so I committed sacrilege and cut a couple of vent holes in the part of the forearm that faces the ground when the hand grips a pole.
