I ordered and received a Sigma #400 water stone from Stu at TFJ and thought I would let everyone know what I have found out so far.
First I like the stone.
It seems to do all the things Stu says it will.
I don't understand feedback from a stone so I can't comment on that.
I used it to flatten the back of a Stanley #80 blade from Hock that I have been working off and on for several weeks with little results.
This stone flattened it up fairly quickly without dishing out. The back and stone remained flat after flattening. No "repair" work when I went to the #1000 Stone.
The finish this stone leaves is really pretty good for a rough stone. My Sigma#1000 removes these scratches quickly. Less time than when I using the #1000 first to sharpen.
This stone does not leave a large burr on the cutting edge. I like that. My Shapton 320 leaves a giant burr.
The stone is hard but does cut quickly. Depending on what your idea of quick is. It cuts about 2 to 3 times faster that my #1000.
Compared to the Shapton Pro 320 it cuts faster and stays flatter.
I have heard from another Creeker that this stone is not nice to the Atoma flatting plate. I use an old Diaflat 320 plate for this stone only.
All in all, I am happy with this stone and would recommend it to anyone wanting a nice #400 stone.
The price seems good to me at about $70.00 delivered.
BTW, Stu refunds over charges in shipping. I thought this was very impressive. It may have only been $1.28 but still impressive.
My other stones are Sigma #1000,#6000 and #13000 from Stu at TFJ.
No problems so far and I don't see any in the future.