I am running Roon Core quite happily on a NUC7PIJH (not that much stronger than your NUC6CAYH). Trying your existing NUC out will not cost you anything and you will see very quickly how much it is taxed. Best to do some DSD to PCM transcoding and then watch on the signal path graph at which speed the NUC transcodes.
You may be surprised how little CPU power it takes.
If you do want to upgrade, I suggest you move to an 8th gen NUC (even if not “officially” supported). I have set one up for a friend and it runs ROCK without a hitch. 8th gen improves over 7th gen in several aspects:
- much larger fan generating less noise
- 8th gen i3 has almost the same single core performance as 7th gen i7 (i3: 4027, i7: 4530)