So... after the recent diamond stone set thread, i started thinking about this one. I have this stone that i use all of the time, and i have a few backups in stock because i had to order a few to get what i wanted. The reason i havent brought this up before is the cost (along with a few other things).
Anyways, let me tell you a bit about the stone:
-It is an 800 grit stone, but it cuts crazy fast (i use it after 150 grit or often times in place of a 400 grit stone)
-It needs to be soaked, but soaks quickly
-it will need water to be splashed on during use
-it wears very slowly, but does wear... mine is 3 years old and i've used it every day for the bulk of my sharpening work (and after my wheel) and its still got life in it
-it needs to be mounted to something (metal, aluminum, quartz countertop, etc.)... its only 3mm thick
-it will eat your diamond flattening stones alive... its important to use the stone surface as evenly as you can
-it works well on all steels, but on soft stainless cladding, it can be a bit too aggressive, so be careful (i.e. ginsanko single bevel knives, thinning soft stainless clad knives like blazen)
-it does not load
-it has amazing tactile feedback and grip
-these are NOT stones for beginners
I've got 4 of these kicking around... they are $400 each. Shoot me an e-mail if you are interested.
here are some pictures of one that i mounted today (and used briefly). This is mounted on the back of another stone i wore through... i cleaned up the base and use it to mount on).