It would be a complete waste of space and money for me, never ever been cold while hiking, I must run extremely warm.My down jacket is one of the most important bits of kit for me. At 200g it weighs about the same as a cotton tshirt and doesnt take up much pack space. As well as wearing it as a normal jacket, I also wear it inside my sleeping bag on cold nights or just wrap it around my feet if they need it. You can just stuff it down your top and keep your chest area warm without overheating.