All I know is, the only thing special about roon nuc's is the OS, Roon OS, I think thats it.
But, Roon Rock OS is based on it and can be downloaded and installed onto any computer. I installed it on my nuc, it took 5 seconds to install, but I had network problems which at that time couldn't be traced, but I've found it and fixed it, so I will try again, and also try audio linux. Both are optimised for sound.
Judging by my Nuc, the roon nuc's should be a decent upgrade in sound compared to a normal computer audio server. I noticed straight away with my nuc that it sounded much warmer and more listenable compared to my desktop which I was using as my roon server. Using usb from my desktop or nuc to my mscaler & tt2.
My nuc isn't running an optimised OS, so roon nuc's may go that little bit further SQ wise. I wanted the roon nuc but then found out it was just an intel i3 cpu on a intel nuc mobo, but the nucleus + is an i7 cpu, but still pretty bare spec wise.
I love these things, everyone should have atleast one, thats how good I think intel nucs are, I should of bought one years ago.