I've been testing this stone since October and have some insights I'd like to report.
When I first received this stone I wasn't sure what I would think of it since I'm kind of a jump from 1k(ish) to 5k(ish) type of sharpener. I sometimes feel that there's no place for a stone that's sort of in the middle. I mean most of the time they don't cut fast enough to be the first stone nor do they refine the edge enough to be the last stone and if you pair stones together correctly (like the Bester 1200x & Suehiro Rika 5k) you can just skip right on by this mid range.
So I received this and used it every chance I got and (no surprise) it seemed to be falling in the middle and looking like maybe it wasn't something that I personally would grab onto.
I was struck by the fact that it has great feedback and that it can be used as a splash 'n go or soaker so I kept playing with it looking for a role to assign it.
I kept using it in between my Bester 1200k & Suehiro Rika 5k and found that the end result was a tad bitier (crisp) but I wasn't convinced that these results warranted the extra time. Then I got assigned touch up duty on my wife's knives (all carbons) and this is where things turned around for me.
I then started testing this stone on every knife that I've got in to sharpen, just to see if it could bring back the deadest of the dead edges and found it to be great at this. I've been surprised because I've never seen a stone do this. Normally you get that fast cutter that creates a burr or you just polish the turd.
What I found is a stone that (simply put) attacks at the perfect rate for a touch up stone. This Imanishi Tamago 4000x stone cuts very fast for it's grit rating, leaves a mirror-esque finish that has a GREAT bite and nearly no burr formation at all and what does form breaks away clean with stropping.
I'm going out on a limb here and say that this stone might be the very best one stone touch up solution I know of. If I was a pro cook looking for an answer to what one stone to use on my gyutos I'd be all over this.
Imanishi Tamago 4000x