well well well.
so i have now used these for a few hours and i will try to sum up how they work.
i used my trusty stainless fiskars @ 52-53 hrc as test medium.
first and foremost these are soakers. quite thick stones at over 30mm.
very hard, i think they are sintered stones with no binder at all. i have also tried the zische missarkas that are also sintered (think a porous spyderco), and those had absolutely no feel at all, they got the job done but wow how boring it can be to sharpen.
the juumas however felt quite nice and creamy, they actually feel really good. not slippery, and not grabby, just the right resistance imo.
they were very hard to flatten on my diaflat! almost nothing happens. they came quite flat, but not completely flat. the feeling of the surface was not changed after flattening. i'm gonna do them fully on the glass plate with SiC since its so much faster.
they dont release any abrasive at all. and wear should be minimal. feels very hard. i did them back to back with the shapton pros 1k and 2k.
and basically these are soaker pros, thats the feeling i get from them, but these will wear slower.
the 800 felt like it was about the same speed as the pro 1k. it left a bright scratch pattern on the SS, a tad finer than the pro 1k.
the 1200 felt almost the same speed but it left a finer darker gray pattern (probably better for kasumi contrast, which i have not tried yet).
the 2k felt about as fast as the 2k pro and it left a finer pattern than the pro (maybe 3k-ish), also brighter pattern than the pro. i liked the finish better than the 2k pro.
the stones are almost impossible to clean. but it doesn't seem to matter, they keep on cutting.
with the naniwa pro nagura = nothing happens, rust eraser = nothing happens. they just pulverize whatever you use to clean them
next i will try the stones on a carbon/iron blade to see if they are good for kasumi.