Very interesting they only ship with Moonsine. I had a grinder several months ago with both burrs that I purchased to compare to my hand grinder (1ZPresso K Plus) and my primary espresso grinder (Key). I also have extensive use (2 years) with a Niche that I used prior to my Key.

My takeaways:

Obsydian Burrs are basically a better version of the Niche. Very similar profile but cleaned up and superior in every way other than perhaps grind time? A Mini Obsydian vs Niche Zero is a clear winner for the Mini Obsydian UNLESS! you doing fairly high volume where you're pushing on the duty cycle of the Mini.

Moonshine Burrs do increase clarity but I don't know that they materially decrease mouthfeel. They're still concials afterall! I think the primary concern is do you want that added clarity? On some dark / italian roasts you do NOT. You want to mute the bitter flavors so the deep chocolates, caramels, and earthy flavors come through and sometimes higher extraction burrs bring off tastes in; this is the same as how classic style burrs can fail to bring out the fruity acids that light roasts bring when ground with modern style burrs. Remember the geometry is the same, the coating is just changing the friction and the moonshine coating creates fewer fines overall which leads to a cleaner, higher extracting cup (I saw one video that showed a 1-2% increase in extraction).

Compared to the K Plus: Obsydian was inferior in every way on my testing. Moonshine was very similar and at times could be hard to distingush. I THINK the burr geometry is the same or very similar based on my eyes so this was not unexpected. Option O says Moonshine is proprietary and K Plus doesn't really say how they finish their burrs but my tastes say they are near identical.

Compared to the Key: No contest. I think Key is the quintessential conical grinder. Moonshine burrs are similar in many ways but lack the overall clarity, sweetness, and complexity of the Key setup. I use the word setup becausse I know based off ample testing that RPM control totally changes the flavor profile of the Key. Lower RPM absolutely increases clarity whereas higher RPM absolutely increases the blending of flavors and overall mouthfeel that Conicals are known for.

In short, I suspect they ran out of Obsydian Burrs in a production cycle and elected not to machine anymore since the Moonshine are really just a better version for the vast majority of people buying it. It's also possible there are some supply chain issues. I'm not sure if you drink pourover or not but if you do at all, then Moonshine are definitely going to be an upgrade and I think my experience mirrors most.

Hope this helps!