I see a lot of posts that ask questions about how to specify a NUC or Nucleus for use in their systems. I get the impression people have bought i7 machines because they were more expensive and gave a sense that you are somehow ‘future proofing’ yourself against advances in Roon. I myself succumbed to that, building a machine with 6 cores and the power to do massive DSP if required. But since falling back to my old OEM based NUC 5i5MYBE in a silent case I could not have not been happier with Roon.
Admittedly my use changed from a DAC that was happier fed DSD to one that is fine with PCM (and can upsample to DSD itself if you want to). Combine that with no more than two endpoints running at any given time, a modest collection of my own music and the fact that in the intervening time Roon actually seems to use less resource for upsampling, and I find myself questioning the need for anything more than my humble 5i5, who’s spec matches that of the i3 Nucleus. So I ask the question, why would you ever need more?
@simon_pepper and I tried to find the ‘break point’ where an i7 could do something an i3 couldn’t. Never got to that point. I really wish someone could find it. Probably need a big library.
I also bought my i7 for pretty much the same reason you did. And even though I ‘intellectually’ know it doesn’t do more than an i3 can, I’d still do it again. It’s crazy.
At least I’m not upgrading my ethernet cables for better sound. 
Crazy, almost as if someone in Roon knew what they were doing! 
My nuc 7i5 sits there bored most of the time too.
I ended up with an i5 solely because I saw a really cheap one on eBay.
I run Roon Core on an Intel NUC i7 over Debian. The same Intel NUC runs HQPlayer Embedded. Depending on the settings of HQPlayer Embedded, the Intel NUC i7 is enough or not.
Bigger processor/more cores = more heat and more noise from cooling fans.
That’s why I love my Nucleus. It’s silent.
And that I fully understand. HQPlayer can need those resources. But I also think that a NUC is not the optimum device to do this on. It is a different sort of compromise.
My Nucleus is perfect for me. But, I have almost no music of my own and never play to more than one zone at a time. I like the little purple lossless light and the sound that goes with it, so I don’t do any DSP.
I would say, always size your core properly based on the rest of your system and how you plan to use it. Don’t worry about “future proofing.” You can always upgrade or sell it.
My i7 wasn’t very expensive really as it was not a nuc and it’s a slightly lower spec than the ones in nucs at that time. I did want to toy with DSP and have used convolution in the main zone , but I am not at the moment. The price between the i3 and i7 model I bought wasn’t much really. I have a lot of zones but really never group them and only two are used at any one time. I am sure the old i3 gen 4 I had may have coped but I wanted to get a more up to date and fanless model and I noticed speeds in browsing after upgrading.