We just got the case closed up and will have it hooked up to the home theater AV receiver in a minute. So far, everything hardware-wise, including the Wi-Fi upgrade, M.2 PCIe, heatpipes, IR, RAM and PSU have been all flawless, thanks in a large part to @confusis’s build photos for the FC8 case from his review. We also installed the drivers from our test bench area with a no-frills full HD monitor, which worked well. Now, we just have to finish installing the other half of the drivers (already installed the chipset, graphics, and Wi-Fi; what is left is the Bluetooth, LAN, audio, and IR) out here. We should be able to connect in the next hour and see how 12-bit color over 4K at 60Hz works.
UPDATE: It works!
Are you using ASRock Fatal1ty AB350 Gaming-ITX/ac motherboard?
4k 60hz works?