Craftsmanship in Wood

I noted a member selling a kanna here with an uradashi-fuyoh blade, explained over on toolsfromjapan as:

The hollowing process, preformed by a CNC surface grinder, leaves a small sliver of 'back' on the blade rather than the small back-and-legs of the more traditional kanna blade. This small area is requires very little time to hone, requires no tapping out and makes this potentially difficult to sharpen blade readily sharpened by most modern waterstones to great sharpness.

There are also photos of an uradashi-fuyoh blade at Iida Tool, which may be helpful.

Now my question: I'm completely unclear how such a blade interacts with the dai over time. It seems that, lacking the sides of the ura, sharpening will gradually reduce the blade thickness. That in turn seems like will cause the fit to loosen.

Can someone shed some light on all this? Am I missing something, or are there indeed significant drawbacks to this style of blade?

[N.B.: I'm not personally interested in such a blade. Between Chris' workshop fall 2015 and even moreso Dale Brotherton's just a few weeks back, I have finally burned away all trepidation about tapping out. But it bugs me that I don't get how the blade fit works here. ]

Hi John,

Just my $0.02 worth, never having used one of these.

You wrote: "sharpening will gradually reduce the blade thickness". That's correct, causing the wedge shaped blade to drop down slightly. That's ok because the blade will also be shorter due to the sharpening.

Gadge