Suggestion (and only if you can do it gently without disturbing anything)

Loosen and spin the slot side hose clamp on the NB block so the screw fitting isn't in the path of a longer pci-e x1 card should you ever decide to put one in there. Someday you may decide you want a longer sound card in that first x1 slot and you would not want the metal of the clamp to touch the back of a longer card. It's easy to do (maybe) now at the beginning than down the road when you've had the unit going a year or two.

If that is too dangerous (leaks) wait and do it when you need it. I'm pretty much going to follow your exact design, unexpectedly since I didn't follow all your buildup, though for me I'm debating water on the mosfets vs air. I like the air for simplicity, but I'm concerned those Thermalright mosfet blocks might get a bit warm. My other change is that I'll probably leave the SB air only without a fan (we'll see).

Love the build, and glad to see you've had fun along the way!