i've use fleece twice to back quilts.
on the first quilt i didn't add any batting. it turned out fine, but was a bit too "transparent" for my liking. i also had a few issues with stretching and not all my squares were still square by the time it was done. it still looked good enough, though, that i was comfortable giving it as a gift. my friend cried she was so happy. :-)
on the second, i added the lightest weight cotton batting i could find. the cotton fabrics in the top clung naturally to the cotton batting. because they are both "fuzzy" the batting and fleece also clung to each other. i only did the littlest bit of basting, but the whole thing turned out very well. no stretching problems, no "see through", either.
the next time i back with fleece, i'm going to try using flannel in place of batting. i think it will work the same as batting does.