Reefable systems require that the furler be able to handle significant torque loads. This requires a ridgid tube or extrusion. If there is just a luff wire or PVC extrusion then reefing is not possible, or a bad idea, because the extrusion will get permanently twisted. Furling also works best on relatively flat sails, and usually when furling say 30% of the sail. Beyond that most furling sails develop a bag shape that doesn't provide much in the way of drive.
Gary H. Lucas