I use fleece backings quite frequently. I will only use the anti-pill kind or Minkee, however. I find that what is often called "blizzard" fleece pills up and gets a matted look, and the longer super soft cuddle fleece is a real bear to work with --- slips all over the place, and sheds when cut; I sneezed a lot. I always use a lightweight cotton or poly batting, and they quilt very easily. Just make an allowance in your thread tension and presser foot pressure to allow for the extra thickness.