My duvet is washable. I have one in storage which was my grandmother's. I always loved it - all year round in southern Pennsylvania. It seems to insulate and adjust, perhaps because it is SO light. Right now, it needs repairs. So we use two light poly- filled quilts, and a heating pad at the feet when it is really cold. That's OK but I do prefer down.

I have a down/feather bed topper that is wonderful to lie down on. I just shake it up each time I change the sheets and it is lovely to kind of sink in to. It is heavier than a duvet so is probably more feathers than down. But I LOVE it! It was only $50 on sale, about ten years ago. Still good as new.