I don't recommend them, although they may meet the tastes of other folks.
I used the 400, 1000, and 6000.
They make coarser finishes than Japanese stones, more on the toothy edge side for the grit rating.
They didn't seem to be very efficient.
The 400 grit cut very slow and was very thirsty and had low feed back for a soaking stone.
The 1000 grit cut fast, but wore very fast and dished in use. Felt more like a coarse stone in use, had lots of feedback but had a gritty feel. Didn't give the edge performance of other 1000 grit Japanese stone, edge was more on the toothy side.
The 6000 grit made a bright finish but was still toothy, more like a 1000grit edge than the 1000grit stone made.
It loads and felt very gritty.
Kinda of reminded me of a mix between a synthetic Norton oil stone and a synthetic water stone but all the bad features of the two.
I think folks that sharpen grandpa style without moving back and forth will like them because they will seem to cut quicker than what they are used to without them realizing it's because it's coaser, also they may experience less dishing with grandpa style.
They also may translate the toothier edge as sharper since it will grab their thumb or bite there nail better when they test the edge like that. Just toothy though.
Not for me.
Maybe a favorite of another, especially if they haven't tried other stones.
Goes without saying they aren't for PM steels with lots of Vanadium
Anyone used these stones yet? They have a few different lines. One line appears to be like an India stone (120 and 180 grit), the other SiC or Crystolon (120 and 180 grit), and they even carry waterstones from coarse to extremely fine grit. I forget the grit ratings, exactly. Like 220-8000 for waterstones. Just curious. Like I need more sharpening stones.