i've used fleece on the backs of many quilts - quilted on the long arm-
they stitch up beautifully!
the one thing to keep in mind is the stretch of the fleece- one way stretches more than the other- figure out which way is which-
and do not stretch it as you roll it up-simply smooth it.
i've done them with batting- without batting- with pieced fleece/minkie
just becareful of the stretch- use a larger needle- longer stitch length- and have fun with it- the kids in my family request fleece backed quilts all the time- they are called the 'get-naked' blankets! they love to wrap in them after their showers :)