Obviously, each to their own.
Mine are used in the
@HiLo Roofs . The bed board does have a 10mm foam under the carpet. I have slept on this with a sleeping bag but was alittle u comfortable. The addition of the Duvalay was just right for us.
Pack size is approx 18 x 28inches(check website) the nice thing for me, with having 2, was that I could use either 1 or two (side by side) one ontop of other etc
Mrs F. is a cold person but found that she was warm and comfortable with the duvalay.
Edit:You can leave them on the bed when you push the bedboard up. But I have not tried it when roof is closed, reason being that my ceiling is 12mm lower that std and my bed it 10mm thicker than std.