Another way to consider things: are you a sharpener or a shaver?
Sharpeners are into it for the shop time; seeking a full knowledge of what the stones do and when they are done. If that's you; more and better hones.
Shavers are all about posing in the mirror, rubbing froth and fat on their faces, and otherwise doddering and freshening up, smelling like a new kind of flower every day: If that's you;
.....sorry I can't finish as I have cracked my self up
I just got my Shapton 16 and that thing is the bees knees. I did get it through that great sale Jenco industries had, so that might make me a little bit more fond of it b/c it was cheaper, but so far I think its great.
After checking out a grit chart that someone complied I forget who, based on the micron means and stdev's provided by the manufacturers, Shapton's 12k=Japans industry standard (new JIS) 8k. Naniwa uses the new JIS stuff. According to the chart I would fully expect 16k Shapton to be similar to 12k Naniwa. Realistically, at this point you're at if not sub 1 micron, so in theory you could get a little sharper but one more step and you're at the sharpest an edge can be (Glen found somewhere that the sharpest edge that our steel's can hold is around .5 micron). CrO, Diamond paste, or a 30k Shapton will get you to/past this .5 micron point, but I would guess that as far as practicality goes, the 12k Nani or 16 GS is all you REALLY need. Because you can only get such a fine particle and no finer...
After checking out a grit chart that someone complied I forget who, based on the micron means and stdev's provided by the manufacturers, Shapton's 12k=Japans industry standard (new JIS) 8k. Naniwa uses the new JIS stuff. According to the chart I would fully expect 16k Shapton to be similar to 12k Naniwa. Realistically, at this point you're at if not sub 1 micron, so in theory you could get a little sharper but one more step and you're at the sharpest an edge can be (Glen found somewhere that the sharpest edge that our steel's can hold is around .5 micron). CrO, Diamond paste, or a 30k Shapton will get you to/past this .5 micron point, but I would guess that as far as practicality goes, the 12k Nani or 16 GS is all you REALLY need. Because you can only get such a fine particle and no finer...