I think after owning the SM580 for less than 24 hours, worked on it for 2 hours to get a proof of concept fit that looks terrible right now, it's a great case. Like everyone says, there really isn't any compromise with this case (or any SFF case that pushes the limit). You pretty much have to plan the build out fairly thoroughly to get everything to fit just right, and custom cables would really help, though very expensive for what they are. Cable management is the nightmare here, at least for me. I see some folks here and elsewhere, not sure how they do it, but damn they're good at hiding the cables. I avoided SATA hard drives and the Front panel to make things easier for cable management, but nope, still a pain.
Will probably redo it all this weekend when I have more time. Right now, it's put together 90% to get a build concept. Good luck!
Now for those with the NZXT AIO, do I need to connect everything it comes with? The SATA power, the Pump header, the mini USB? Right now I have my fans connected to a board header with a y-cable for each set of 2. Trying to see if I can cut down on the cabling. Gigabyte x570i Wifi.