Re: the heat problem, my parents gave me a sheep woolen duvet a while ago (Texeler brand, kinda local to NL though) - it's not a knitted or scratchy contraption, it's a duvet like you know them. However, it's a lot heavier than normal duvets (about twice as heavy I'd gauge), and it's perfect in terms of heat regulation - even in summer I can sleep under the covers without feeling too warm or sweaty. I think the problem with the heat of weighted blankets as mentioned here is down to the materials used, non-permeable plastics and glass and the like.