I’ve been using Roon Core on Ubuntu on my mini PC (GMKtec NucBox5/N5105/8GB/128GB) for the past two years without any problems, and I completely missed the fact that ROCK is now UEFI compatible, so I replaced it with ROCK this weekend.
It boots up fast, and Roon ARC is working fine.
It’s easier and better than Ubuntu+Roon Core.
Strangely, I’ve gone the other way - at least in part.
I was running RoonOS (as installed by ROCK) on my NUC11TNHi7 until about a month ago when I changed over to DietPi (Debian based linux).
I did this primarily because:
- It allows me to monitor temperatures and memory usage which I can’t do with RoonOS
- It allows me to configure scheduled tasks to keep the OS (not just Roon Server) up to date.
- It supports later versions of SMB so the network share used to manage the media library (not the Roon Database) is username and password protected.
When I was using Ubuntu + RoonCore, I could check CPU usage (always around 20% even with DSP turned on), see CPU temperature, update OS updates whenever notified, and do many other things, which was interesting at first, but it became somewhat bothersome and I chose the easier way. 
My NUC is tucked away in my lounge and is generally inaccessable. When using RoonOS, I had to periodically (once every three months or so) pull the NUC out and visually inspect it for dust and debris that may be interfering with the cooling and then remove that dust.
Now that I use DietPi, I have found that the processor package temperature generally runs at about 7 Celsius above ambiant (when the server is idle) and so now I hope to be able to use this knowledge to tell me when I need to clean the NUC without having to remove it first. This should make things a lot easier.
For example, when the processor starts to run at, say, 12-15 degrees above ambient, then it may be due for a clean.
Of course, I’ve yet to see how well this will work because I had to remove the NUC to install DietPi, and, whilst it was removed, I gave it a good clean so it has not yet got dusty enough for me to test.
My mini PC is in the storage room where the equipment that collects the power and network for the house is located, so it has been installed for 2 years and dust has hardly been a problem. I do clean the amp in the living room regularly as the fans do indeed get dirty with dust.
When installing ROCK, I blew the inside of the mini PC with an air duster and found very little dust.
There are many ways to run Roon Core depending on where it is installed.