>>2038652/2
The thing is that a lot of these "serious" backpackers use wool clothing. An advantage to a cloak compared to another layer of shirts is that it traps warm air inside of it, which is going to distribute warmth from your core to your extremities. This is how sleeping bags work, and why down-filled onesies aren't (and never will be) more popular than mummy bags. To test this concept, compare how warm you feel in normal pajamas as compared to a bathrobe of the same material in a drafty house. Yes, there are going to be drafts when you walk with a cloak, but for activewear? I don't think that's a major issue. When you stop hiking, you will get colder, but you can also button up the cloak. The fabric is still going to block wind relatively well when you're moving and are getting drafts.
The real question is whether a wool cloak is activewear or not. I've found, time and time again, that even in the coldest weather I've hiked in, all I need to stay warm while hiking is a single base layer and a single wind-blocking layer shirt/jacket plus plain pants. When hiking in 20-40 degree weather, this is enough - I might add a second base layer shirt below 25 degrees, or remove the wind layer above 40 degrees. When I stop hiking, I immediately get cold in these clothes, but for this down time, I will immediately don a puffy down jacket, and again, this is enough. Most "serious" backpackers I know use a similar system.
Can a cloak replace a puffy down jacket for breaks? For that matter, is it even possible to hike with a cloak under a backpack, or does it go over a backpack? If over, then how do you keep the back close enough to your body to take advantage of its warmth? If its intended as part of a sleep system, then how are you going to keep it dry when hiking through wet grass? To me, these questions leave me with an unsatisfactory piece of gear when looking at cloaks in context of hiking. YMMV.
