a coworker got one recently. I tried it on an out the box kizer beglieter and the 20 degree angle did not reach the edge.
I like the concept, but have concerns about the abrasive being used perpendicular to the edge, but maybe I'm over thinking it.
it was very simple to use and under some magnification I could see where it was removing material from the bevel behind the edge with just a couple minutes of use.
I will probably test it further on some beater knives once they get a chance to use it a bit.