Deejay, I like that gadget because it helps to keep the edge square to the top surface of the bedknife, so less skill is required than with a hand-held oil stone. Don't forget to keep the oil stone in the gadget oiled when you use it, of course, and be careful to remove all of the abrasive and steel grindings from the bedknife when you finish.
It is a bad idea to backlap a reel if you are going to reverse it later, because it has then effectively been forward-lapped, and will have a rounded leading edge on the reel blades. Also, backlapping tends to leave a slight burr on the leading edges of both reel blades and bedknife. This should be removed with a stone or your cute little gadget. Removing all of the grinding compound after backlapping is essential, and note that valve grinding paste is normally emulsified in oil, not water. It will not wash off with water.
