The Kaze is an excellent sword by the standards of a differential temper
I won't argue that the Kaze cuts like anything less then a lazer. In fact, the Cheness website recommends sharpening all of their swords before putting them to use as they don't come with a razor edge out of the box. This is true, though my experience is that their descriptions are a bit too self deprecating, both swords I received from them were better then their description suggested. However, as nice a sword as the Kaze is I feel that differential temper blades that are not of collector standards,in the sense that they have solid investment potential, are rather pointless. I also bought a heaven and earth sword, a through hardened blade and it is not only tougher, but has better balance and just feels better in the hand.
Cheness swords are made for practitioners not collectors, so it just makes sense to buy the cheaper blade with more resiliency and better performance. Of course this is jut an opinion, I make no pretense of being an expert.