I haven't held a Kato. But, in my opinion, the best performing grinds use asymmetrical grinds to achieve something that has a lot of convexity but is also really thin behind the edge. The thickness from the middle of the knife up to the spine doesn't really matter as much. That is why that knives can be very thick at the spine but still thin behind the edge and still convex. Here's a few choil shots I will try and show what I mean.
The knives I really like usually have geometry that looks like this
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This is for right handed. If you are looking at the choil, gently accelerating convexity on the left side spine to edge. Super flat or slightly concave on the opposite side ground high up the knife. If my knives don't start with this geometry then they will eventually get it because this is how I sharpen them. I think that this gets you something that is thin behind the edge and also convexed some for strength and durability (especially when combined with a microbevel at the apex).
Watanabe is gentle convex on one side and gentle concave on the other to result in very thin behind the edge
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Shi.han grind is similar. Gentle convex on one side, extremely flat on the other, not quite as thin behind the edge as watanabe. But give me a few more sharpening sessions and it will give it a run for its money.
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My Tosa Nakiri takes a different approach. Kind of an inverted coke bottle shaped figure from the factory. Thick at the spine. Concave spine to middle where there's a slight thickening and then concave again from the middle down (slightly concave bevels). Extremely thin behind the edge. Too thin. This isn't stock, I have flattened and started to convex the bevels to strengthen them. But it does show how you can get some nice convexity out of a fairly thin knife.
And lastly. Here is a forgecraft 10" that I have put a lot of work into. This knife is less than 2mm thick at the spine. Still plenty of room for convexity on the food facing side.
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