Alright, first-round experience with the knife tonight!
I diced up bunch of carrots, celery, tomatoes, potatoes, and peppers and sectioned up a whackload of tomatoes. I think the knife takes a nice edge - certainly no problems with tomato skins and pepper skins even though I did them pretty much last. However, I think the profile height and the flat-ground geometry towards the edge keep this nakiri from being the best it could be.
In terms of the geometry, the blade reminds me of my Takedas but is considerably thicker. Practically slab-sided faces from spine to at least the halfway mark, and then flat ground from there to the edge. The "slab sides" aren't entirely perpendicular to the cutting surface, there's some taper, but very little. I think the Takedas get away with this approach because of the overall thinness of the blades. The Yamawaku, however, ends up wedging through hard veggies like carrots. You can hear them cracking rather than getting cleanly cut. For tonight's mix of veggies, I only noticed it on the carrots. The Takeda has a bit of this too, which is why the Takeda nakiri wouldn't be my first choice for carrots either.
Whether it's a function of the geometry or the finish, I have to say that the knife did wonderfully well with Russet potatoes. No sticktion issues at all. Maybe I should try out some Yukon Golds to see how they do
Onion, tomatoes, no problems.
The profile height thing is purely a matter of personal preference. Comparing with my other nakiri, there's about a 3-5mm difference in height. Technically not a big difference, but somehow it made a difference in feel. I know I prefer taller blades in general, even with gyutos, so this may not be anything at all for other users.
I'd like to go through some more veggies and spend a bit more board time with the knife, but those are my initial impressions from tonight!