If it is the same as the backing, it sounds to me as a perfect addition to your quilt.
However, I do have a question that I will throw out here, that's always been in the back of my mind about using flannelette ginding. Honestly, I don't know the answer.
Question ... is flannelette binding more apt to break down or wear out faster than traditional quilting cotton?
Answers ... ???
Thank you!