http://www.stewmac.com/Luthier_Tool...wning/StewMac_Z-File_Fret_Crowning_Files.html I was thinking about grabbing an offset diamond file deal from Philadelphia Luthier Supply, but then I saw this on Youtube. Seems like it would be easier to use than either an old-fashioned 3corner file or even an offset file. The few reviews I've seen for it are rather glowing, save for the price. But I want more on-hand experience. Anyone here use one?