I didn't know about these until I seen burr king's the other day. The cost I saw almost doubled the price of the grinder. I just looked up the one you have and that is a more realistic price (for me).
This all comes at a time when I was recently researching vintage surface grinding. I didn't get very far - just not much internet time - but I realized draw filing was the best I was going to get for now. My family read a biography on Alexander G. Bell and he was constantly working with machinists trying to perfect his invention, so I know there's a way to do it old school style until I get a good grinder. I could see this attatchment as a very valuable addition. What speed do you run when you use it? Glad you guys were ok in Anchorage we never felt it up here.
Luke