Wow, these are all incredibly impressive!
That's good to hear about the fan. I was quite disheartened when I fired up my 6626A for the first time to find that I had actually bought a jet engine, and that's after buying a slightly lower dB fan to replace the bad noisy fan it came with.
It makes sense about the 24/7-in-hot-rack expectation, but I guess I never fully considered it! I actually considered a Noctua when replacing my fan, but got scared off by the way lower CFM.
Anybody rigged up a temperature sensor to make the fan spin up as the heat sinks get hot or anything fun like that? Any kind of noise considerations you need to take into account when futzing around and adding fans and wires to the inside of the PSU, especially in high-precision units such as these?