Hrm...no idea how I got the idea that you were getting a Kuromaku 12K as well. Oh well, Hein31 answered my questions in regard to that stone. Kind of doesn't surprise me, since Shapton in general are said to create a harsh edge compared to Naniwa etc. I suspect as Onimaru said earlier that pressure plays a lot into that. Less is more.

If you get a chance can you tell me what the shave is like off the Kuro 8K? That would give me an idea what to expect off the 12K I think.

Not that it's too pivotal. I don't necessarily want a 12K finisher as much as I do a synthetic beyond 8K to use as a base of comparison. And I've got plenty of naturals that could be used to soften up the edge if it were too harsh to just let stropping take care of it.

Your comparison to the 4k is also helpful. I'm not surprised the jump to 5k seems to take a while. 1k to 5k is quite a jump, and I suspect the Kuromaku stones were designed to have the 2k or something else worked in between 1 and 5. Which is a bit different from the Norton hones, which were designed to allow that 1k to 4k jump.