We had last week a fantastic meeting of Revopoint freaks in Munich, organized by @Truderinger. We had plenty of fun, we found plenty of common topics, and there were plenty of discussions about our own projects.
One of the topics was about the smallest marker that is recognizable by a Mini. As I have the tools to make my own markers, I have prepared this setup, with 4 different diameters (1,5mm, 2mm, 2,5mm, 3mm) and run some tests with my Mini & MetroX.
The result can be summarize here: The color means:
Green: Markers visible 100% of the times
Red: Markers never visible
Orange: Markers ocasionally visible (10% of the times, approx)
So, the Mini is able to work with 2,5mm markers. Anything smaller than this is just unusable.
BTW, this test also matches the observations from @kaczorefx. 3mm markers on the MetroX only work in laser mode.