Hmmmm, is the roller a ball or cylinders that roll? If it is cylinders I can see it rolling frontwards and backwards but it wouldn't be able to go sideways. That is the same problem that I have with my walking foot when quilting a quilt. It is hard to maneuver a quilt through the harp being only able to go in one direction. Now if the rolling foot has a round roller that lets you stitch in any direction? I could see that working for FMQ. You will have to try it out and give us an update.