I have also used a similar unsupported wire system on two kayaks, before switching to double line control. The usual way this system fails is if there is more friction on the slider part of the system than on the blade. I use thin washers (cut from camping mat foam) to create the correct amount of friction at the blade, and keep the cable and slider as friction free as possible. The double line system I have been using for some years is even better in this respect – with the added bonus of more leverage to free a jammed skeg by pulling a downhaul line than by pushing a wire.