I think flannel is a great alternative to higher loft. I used it as a back on a throw and it was great but there was a drag when I machine quilted, so if I do one again I'm thinking I won't use the flannel without an cotton back, plus the flannel on the back would make it a magnet for grass and twigs ( remember most of us have design walls that are flannel and things cling to it) but inside as a batt it would be fine.