Active Shell is the most breathable and lightest weight Gore-Tex fabric and is only found in minimalist garments designed for aerobic activities. Mountain Equipment says the Supercell is designed for “fast moving trekking and backpacking”. I think you can move slowly and still find this a good jacket however. It’s the lightest jacket tested (by one gram!) and the fabric is soft and flexible, making it comfortable to wear. It’s reinforced on the shoulders and lower back for wearing with a rucksack. The hood has firm stiffening that doesn’t distort in the wind, unlike some hoods, and allows good side vision. The external pockets are fairly roomy but not quite large enough for maps. However, there is a stretch map pocket inside the jacket. The length is slightly longer than many rain shells. The cuffs are wide enough to allow some airflow in the sleeves. It is close fitting so a larger size than usual is best if you want to wear it over a fleece jacket.
Of the sub-400 gram jackets tested this is the best, combining good design and a top quality fabric. Some shops should still have stock of the Supercell. However, it’s been replaced by the similar Cascade jacket, which has a roomier fit and extended reinforcements for better wear with a heavy pack. The Cascade costs £10 more and weighs a little more at 365 grams.