As indicated from a previous conversation ( http://chowhound.chow.com/topics/7661... ), I was considering to purchase a stainless steel Santoku. At the end, I bought the JCK CarboNext Santoku which is a carbon steel knife. First, let me say that I am extremely impressed by Koki Iwahara's delivery speed. I ordered on May 17th, 8:00PM, Koki shipped out my knife within 3 hours, and the package was attempted to deliver to me on May 20th. I wasn't at home, so I picked it up today on May 21th. This is fast for a shipping from Japan.
As shown in the first photo, the CarboNext Santoku (bottom) is placed next the Tojiro DP Gyuto (top). The Santoku is a shorter but wider knife. Its fit and finish is fine. The handle is dark brown and it is rounder (less boxy) than the Tojiro. The edge profile is more curved than I would have wanted. In the second photo, you can see that CarboNext Santoku (top) curves up about the same as the Tojiro DP Gyuto (bottom). The photo may actually shows the Santoku more curved, but I double-checked, they are the nearly the same. The factory grind is indeed asymmetric as advertised. It is asymmetric with different angles. In other words, it is #4 in this following picture:
The factory edge was fine. It sliced meat just fine. It shaved my arm hair at least from one side of blade and could push cut on printer paper -- though not very smooth.
I reprofiled the knife with a final ~10o symmetric grind. It was not too difficult to sharpen, and burr formation was easy. After completion, the new 10o edge could better push cut paper. I sliced off some more pork shoulder meat. It appeared the edge was duller after the light task, but could still shave my arm hair and push cut paper – it just felt less smooth. The knife can stain/oxidize a bit, but it is very faint. It indeed has good rust resistance for a carbon steel knife. This is my very first day experience with the knife. So far many of the rumors have been proved to be true. The edge retention is not as good as I had hoped for, but I did reprofile it all the way down to 10o. It is very possible that 10o each side is too acute for this knife. I will most likely bring it back to 15o like my Tojiro knife. I know my Tojiro also had troubles holding the 10o edge angle. I will have to play around with this knife for 2 more weeks to get a better feel. So far, it seems to be on par with a VG-10 knife. It does not seem to have the same hardness and edge retention as my Tanaka Aogami Nakiri.