Nice disassembly and pics, saves me snapping my poor ones when I take a look.
Were there any grinds trapped in the burr housing? One of the M3 claims was that this had been eliminated.
I've done
two blind test cuppings so far:
* One of a slightly tainted coffee with one cup from each grinder. I had gotten the taint from shots, but not at my previous cupping (done with the mini before the M3 arrived). One cup was very vivid, and much worse, because the it was vividly tainted; the other was mute and blah. I was very relieved to find the vivid cup was the M3's.
* The other was of a 90 plus rated coffee, cupped in a "triangle-test." This involves six cups, three from each grinder, arranged in two groups of three, each with one odd cup (from the other grinder). The task is to identify the two odd cups. This one had me sweating. In one group, one cup was a lot more vivid when breaking the crust, and I decided it should be the odd M3 cup mixed with two from the Mini. In the other group, I looked for a dull cup, and had a very tough time, settling in, very tentatively, on one suspect. However, the task got wonderfully easy when the cups cooled, since the M3 cups stayed clear and bright, whereas the mini cups got muddy with overextraction. (My tentative suspect proved guilty)
I'll do more tests (when I feel like tempting fate again); but we're down to 1 in 18 the results being chance, 17 in 18 that the M3 grinds distinctly better for french press or cupping. In terms of the grinds resisting overextraction (or having fewer fines), I'd rate the difference a complete certainty, since the cup differences in both tests became utterly obvious as the cups cooled.
This bodes very well for me, since I bought the grinder on the premise that fines are what makes SO espresso from very bright coffees, delicious when brewed, undrinkable as espresso. So far the shots I've had follow this theory. The M3 shots are considerably snappier than the Mini shots (the good part of acidity), but have never been acrid, sour, or lemon-peely (the bad part of acidity).
These results are preliminary. I judge them pretty conclusive on the brewed front, but very subject to revision from blind tests on shots.