I had one of the first of these to be sent out. I tested it extensively for a couple of weeks then moved it on. For me, and I totally accept that it might have been my poor preparation but over the Evo Leva the gain for the additional problems was not worthwhile. Personally, I think the step down is too great. For example, going from a 58mm group to a 53mm group the advantages of a narrower but deeper puck were substantial.
The guy who designed it bought a DF53 for testing purposes. We fell out when I pointed out to him that unless his target market was the 53mm burr set he had bought the wrong grinder as far more of his customers would be 64mm plus range. I suggested when fine tuning he would encounter issues specific to that size……and here we are.