I'm looking to purchase both over time, in the 240mm size. Unless I find something else later on.
Your opinions are greatly welcomed
Mizu is Aogami #2 carbon clad in kurouchi carbon. As with other kurouchi carbon jigane / carbon hagane san-mai knives, the kurouchi finish will provide some protection against corrosion but is far from impervious. All kurouchi finishes eventually wear off, some faster than others. I don't have any experience with the Mizu to compare it with known quantities like Takeda (hard wearing) or Moritaka (goes quickly) to place in on the kurouchi continuum. Just be aware, that at some point you'll be looking at an unfinished carbon knife, and will have to do something one way or the other to keep it stabilized and corrosion free.
Yuki is Shirogami #2 carbon clad in stainless. As with other stainless jigane / carbon hagane san-mai knives, the hagane is well protected, but you should take steps to keep the edge from corroding. You don't have to grow a patina; just keep it clean and don't let it sit around wet and/or dirty.
If you want more information on either or both knives, I suggest joining the CKtG forum. There's a lot more experience with them there than here.
People who keep carbon knives learn to wipe them frequently during prep; to never leave the knives out when prep is done; to rinse thoroughly; and to dry completely -- towel, followed by at least a few minutes of air-drying -- before putting them away.
That's the right way to treat any good knife.