Additional info for anyone building with this. The midplane fans respond only to HARD DRIVE temps, not to the motherboard. The proper alignment with the pins for the fan headers is to have the 2 blank pins aligned with the side of the PWM headers with the clip, and the final tach wire not in contact to the motherboard PWM header. If you swap the motherboard, I would recommend an active 2U heat sink at least for the back CPU in a dual socket config, as there's just a hair over 110mm clearance off the motherboard to the top of the case, I'm not planning to try a Noctua 3U active cooler. With HDDs it's entirely possible that the amount of airflow through the case would be sufficient with passive cooling, however I did have thermal throttling in testing with no HDDs. Still waiting on those caddies to finish printing.
Instead of rails, I've opted to try 1U star tech shelves capable of holding 200lbs. All in all, this seems like an excellent budget chassis. Replacement parts may be non-trivial to come by (Fans/PSUs) so keep that in mind if you're buying to be cheap for a small business/low budget operation like me.