personally I would not put a satin binding on a flannel quilt. The flannel is going to be washed heavily over time and the satin will most likely not hold up the same as the flannel. If you want a shinny look, try a poly/cotton fabric that has a sheen. On the other hand it would depend somewhat on whether you are using satin ribbon as usually seen on ready made quilts or a satin bias tape. But think of the washability and use of the quilt.