A quick look inside, here. It’s clear that Fractal has has a hand in designing the board layout and specifications, as their name is all over it.
Not being a PSU engineer, I can only comment on the quality of the components to some degree in that I can observe great care taken in trace routing, Japanese 105°C capacitors very finely done soldering with no “arc” tails or sloppy overruns on the pads, heat sinks in all the right places, and no extraneous or “bodge” wiring.
If you look below at the two internal shots here, you can clearly see the 550 and 850 are closely related, as there are just a few main components missing from 550 – as well as the tolerances of the ones that are there. The MOSFETs all appear to have good heatsinks, and everything is spaced out nicely to prevent heat-bleed between components as much as possible.