This is an updated version of the original "Grinder Shootout III" originally posted on Decent Diaspora.




The Grinders
KafaTek MAX SLM (98mmn flat Shuriken light/medium burrs)
KafaTek MC4-Duo (dual conical with pre-grind stage and 71mm final stage)
Versalab M4 (hybrid with conical breaker and 68mm flat finisher)

The Testing Method
Four hundred shots were pulled for three people over eight months. On days when we were all home, I pulled one shot off each of the three grinders. I wrote the three grind settings on the coffee bags to make this easy.

The Beans
We used several dozen different beans, mostly single-origin. The roasts ranged from light to medium, but primarily light-medium filter roasts.

The Espresso Machine
Decent DE1Pro.

Usability-Noise
I used the dB Meter app on an iPhone 12 Mini and held the phone 12" from the grinders. These values give at least a relative sense of the noise.

(Noise running with no beans)
KafaTek MAX SLM: 30dB
KafaTek MC4-Duo: 40dB
Versalab M4: 25dB
(for comparison Forté: 75dB and Niche: 48dB)

(Noise while grinding)
KafaTek MAX SLM: 42dB
KafaTek MC4-Duo: 42dB
Versalab M4: 75dB
(for comparison Forté: 80dB and Niche: 70dB)

Of the three grinders in the shootout, the KafaTek MC4-Duo is the most pleasant sounding with its low growl while grinding, and the Versalab M4 is the least pleasant sounding.

Usability-Workflow
KafaTek MAX SLM: RDT, WDT, Tamp
KafaTek MC4-Duo: WDT, Tamp
Versalab M4: Tap and Tamp

Usability-Grind Speed
KafaTek MAX SLM: 40-60+ seconds depending on how easily the bean feeds. (With the original SSP LU burrs, it was about 15 seconds.)
KafaTek MC4 Duo: 35 seconds
Versalab M4: 15 seconds

Weight
KafaTek MAX SLM: 26lbs (12kg)
KafaTek MC4 Duo: 22lbs (10kg)
Versalab M4: 36lbs (16kg)

Ease of Pulling Shots with no Channeling
All three grinders are much easier than the MAX used to be with the original SSP LU burrs (faster puck erosion). But of the three, if there's a rare sprayer, it's on the MC4-Duo. I expected the MC4-Duo to behave more like my daughter's Niche, but it requires better puck prep and seemingly has fewer fines. I suspect the height of the final coffee bed is a factor. Using a 20g dose, it's much shorter with the MC4-Duo than the MAX.

Taste
I realize some people want more traditional generalizations about the three burrs, but I'm not confident enough to make them. I've also noticed what flavors show up is highly affected by the profile and recipe I'm using. So this may be an unsatisfying section for some, but I'll simply share a few taste observations I find interesting.

The KafaTek MAX SLM creates more overall flavor with some beans than the other two grinders, but I think it's slightly more blended than the original SSP LU burrs initially installed on my MAX. With some beans, those flavors stand out more (in their slightly blended way) than what I can create with the MC4-Duo or M4. Also, I often notice lovely acidity and sweetness with the MAX SLM. But with some beans, the MAX SLM is distinctly in third place. It would be interesting to taste with someone like Luca Costanzo to see what's going on, but I wonder if there are aspects (or defects) in the roast and beans that also show up as part of the "more flavor."

The KafaTek MC4-Duo creates a sweet, balanced shot with more clarity than the other two conicals I've used (Niche and Ceado E92). One way to describe MC4 shots is that there are fewer edges--good ones or bad ones. I've noticed the "oh wow" the three of us have with the MC4 is the highly contented type. With the MAX SLM, the "oh wow" is more like sitting up and paying attention. There's usually not a lot to dislike with the MC4, but sometimes a lot to love. My sense of the KafaTek MC4-Duo has evolved since the original post on Decent Diaspora. I'm enjoying it even more now that the burrs are seasoned, and I know what I'm looking for when dialing in shots.

The Versalab M4 doesn't always produce quite as much overall flavor as the MAX SLM, but sometimes it seems to create a bit more separated flavors. That's surprising given the MAX is a 98mm flat burr, and it could be observation bias when the DE1 profile/recipe happens to fit the M4 better for a particular bean. We've been enjoying an Ethiopia Worka Chelbesa Anaerobic from Onyx, and on the M4, it's an immediate and unmistakable "strawberry." On the MAX it's an immediate "wow, that's a whole lot of berry" and then "oh, that's strawberry." The M4 produces a distinct and narrower strawberry flavor, while the MAX produces a strawberry flavor with an interesting depth and complexity.

Quirks and Qualities
The KafaTek MAX SLM is designed to feed slowly for flavor improvements, but with some beans, it's frustratingly slow. And, every now and then, a single large bean won't feed. This is easily solved by turning the grinder off, gently tapping the bean with the wooden handle of my brush, and turning it back on. Also, there are two power switches. If you leave the rear one in the "on" position, there's a bright LED switch on the front that's intense and distracting. Finally, the MAX has never jammed, and I doubt it will.

The KafaTek MC4-Duo has fed every bean with ease and never jammed. But sometimes, there's a bean fragment that produces a squeak. The squeak goes away during the next grind when the coffee bit is freed. Also, the plastic insert in my spout was too loose and sometimes fell out. Upon inspection, there was a hairline crack. Denis sold me another one, but it also arrived cracked. Finally, if you are not careful, it's easy to knock off the spout held in place by magnets (true of the MAX too).

Except for the intense and somewhat unpleasant sound when grinding, the Versalab M4 is a joy to use--simple and repeatable. But one quirk is the weird plastic cover (to stop popcorning) you have to lift when pouring in beans--it's clunky and feels cheap. In the original Decent Diaspora review, I said the M4 fed almost every bean I'd thrown at it, with two exceptions when it jammed. Lately, I've had two more beans jam even with a hot start (grinder on, then pour beans). Interestingly, the problem some people have with "logs of grounds" falling down after grinding has been completely eliminated by doing a careful fruit waxing of the bottom funnel.

Conclusions
I like all three grinders for different reasons. The Versalab is now at a different location where groups I work with meet. The MAX and MC4 are side-by-side in my home. I purchased the MC4-Duo out of curiosity and assumed I would sell it at some point, but I'm enjoying it enough that it's staying.