My concern is for the OS and software on the NAS, not the hardware.
I am biased against tweaking a device away from its original purpose.
I agree with @Ratbert; “A NUC running ROCK operates more like an appliance than a pc, I find it the ideal solution.”
The trend to small, single purpose devices is a great improvement.
The general purpose computer was a huge innovation, but as the hardware got cheaper, the management of the complex setups overwhelmed the hardware cost. (I say this with embarrassment as I spent 25 years working on systems management.)
A NUC that does nothing other than Roon is a great appliance. Running ROCK instead of Windows or MacOS simplifies it further.