Last night I used the new Stew Mac Fret/Fingerboard Leveler. It was not very exciting... it worked but no better than the Stew Mac Aluminum Radius-sanding Beam.
The bad: Not worth the money. One of the large flat surfaces should have been milled.
The good: It is heavy, long, and pretty flat. 320 grit sandpaper leaves fewer marks than the extra-fine diamond sharpening stones or my files.
Still not satisfied maybe it is time for a Plek Machine.
The nut seating files from Stew Mac are the greatest leap forward in nut seating technology since the chisel.