Funny enough I was just talking the other day with some people about the same problems: in the end nothing is really waterproof and breathable. Only a plastic poncho will 100% protect you from the outside wetness , while creating a sauna underneath
I went for over 3h in cold wet snow conditions and I got completely soaked in a high end DryQ Elite jacket, with only one t-shirt underneath. I changed into a dry shirt as soon as we stopped for lunch and had some warm soup that I brought in a thermos container. This combination kept my body temperature warm enough to spent another 3h in those wet conditions. My 2c..of course.