In reply to Wildabeast:
Just so you know I am supported by Montane. I am guessing you are asking about the extreme smock? If so it is a brilliant winter climbing garment, and I wore one for Scottish winter for years, as did most of my partners. It works for moving together or pitching. Won’t really work for full on speedy soloing or hillwalking if you are fit, you will get too hot. My suggestions are : don’t wear it on the walk in. For a pitching day put it in your pack and , as carry one belay jacket between you and your partner. Walk in in lighter stuff, base layer and wind proof most days, might need a waterproof on wet days, start off cold from the car but with a warm hat and gloves . At the kitting up spot strip off sweat soaked base layer and wind proof and put on extreme smock. If you are above the freezing line you don’t need a shell on top of the smock, but make sure you either have the extreme hood or a balaclava. If you are pitching lead and follow in the extreme, and put the belay jacket on for any belays that will be more than 15 mins long, i.e. most. If moving together you won’t really need the belay jacket. All this assumes you are fit enough to keep moving most of the day, you eat enough , you don’t climb in the rain, and you avoid climbing in the teeth of gales.