The change in hardness improves sharpening in that respect as you are only honing a thin piece of hard metal not the full width. I suspected at first that it might cause an uneven grinding due to the quicker abrasion of the softer metal, but have not found this to be the case. It is probably due to the concentration of force near the edge when honing, if you leaned more into the upper part of the bevel it might get lop sided.
The UHC blades I would be interested in feedback as well. I have asked around and got very limited feedback, however what feedback I did get was not positive. Yes they appeared to hold an edge well, but not nearly as what would be expected given the hardness levels proposed. Sharpening a very hard edge in that manner I would also not think is very efficient.
-Cliff