After enjoying the thin draft flap, instead of tube, on a Montbell down spiral bag, decided to use a thinsulate draft flap for the next DYI bag. May leave the gauze in for stiffness.
There is also Thinsulate Liteloft, a totally different product, that has considerable loft and a much better warmth for weight ratio than the regular Thinsulate. It has the very thin olefin fibers for warmth, and larger fibers for loft. OWF stopped selling it way back, because, they said, it was too expensive. Have heard there are loft retention issues with it, but have not had any with a bag I made of it. Plan to use it again for a bag made with .67 oz nylon purchased a while ago on a group buy made through this forum. Will use the Liteloft like down, but with fewer baffles than down, and with the baffles made of very light panty hose material.