When we started out on our walking career we bought over trousers, I wore them once and have never bothered since, I found the sweat from the inside is as bad as the rain on the outside and because the rain is generally accompanied by cold weather 'Breathable' fabrics should work but don't in my experience.. I find lose fitting clothing best, the rain pelts down and the wind blows, the fabric flaps around flicking the ain off meaning the rain doesn't soak through.. I have been soaked to the skin by failed fabrics, water getting in through holes ( neck, arms, open pockets, tops of boots and poor stitching ) there is actually not much you can do about it but find a distraction and know that getting wet is part of the whole outdoors experience. Spending £hundreds to stay dry is all OK if you have that sort of money to buy, replace and spend time maintaining the apparel.. I prefer to keep the extremities protected, gloves, hat, socks ( carry dry spares ) neck tube, fleece layers.. there is a lot of clothing you can carry that doesn't take up much space or weight.. Getting out is the most important thing, keeping dry might just mean carrying a brolly ? The Weather is different every time, there is so many different types / permutations of Weather, keeping dry is difficult, coping is the best method.. Mountain climbing is a different kettle of fish, keeping warm and dry is very important when hanging off a cliff at 4000ft..