Not sure which model is which, but get the one (or the update kit) that features machine screws and knurled brass nuts to secure the hopper to the base. My early version used some coarser threaded screws that screwed right into the plastic hopper, and if you got careless/hamfisted, you cracked the hopper. The machine screw/brass nut version is much easier and prevents cracking the hopper.
When changing disks, just loosen on of the screws about half way. Hold the whole contraption over your bench because as soon as you raise the hopper the two aluminum riser plates will fall out, you want those to fall in a convenient location. Hold the hopper down against the disks and then completely remove the opposing nut and screw. Raise hopper the 1/16 - 1/8" or whatever and rotate it 180 degrees.
After replacing the disks with the desired combo, reinsert one of the riser plates in the side that still has the screw backed only half way out. Rotate the hopper so it's lined up with the holes and hold it captive, Barely snug that screw up and then insert the second hopper riser plate on the other side, insert screw and tighten up the nut.
Sounds kind of difficult, but after you do it a couple of times, it's pretty easy. Takes longer reading through my convuluted instructions than actually doing it.
Because of this, I've toyed with the idea of picking a set of disks that would throw a charge just a couple tenths greater than what I'd want, and then drilling a tiny pilot hole through the larger of the two cavities and expoxying in a threaded sleeve for a set screw. I'd use that set screw to fine tune the volume of the larger cavity to preclude having to disassemble the works to swap out disks. Anyone try such an endeavor? Thoughts? Would epoxy work on the disks? They are some kind of nylon material, and I'm not sure epoxy adheres to this, that's my only thought so far that's keeping me from trying this out.