Hey Derek,
overall, the spec looks pretty good - 16 cores should be perfectly fine; I suspect that a typical Cantabile song won’t always be able to make full use of the number, since a lot of things will need to be processed in sequence, so difficult to parallelize. So single core performance will remain a crucial element of system performance.
The one thing I am wary of is the whole NUC architecture concept - essentially, it builds on laptop technology, including all the power-saving mechanisms involved in maximizing battery life. And these same mechanisms keep us live audio musicians in constant pain - some of them are extremely intrusive and resistant to de-activation…
Personally, I prefer small form factor PCs - my current “LiveCubes” have been built on the ASRock DeskMini platform - it allows the use of desktop processors up to 65 W.
Thermal load is overall a key limiting factor for small form factor devices - the more cores you add into the equation, the lower the CPU speed needs to be kept to avoid “meltdowns”, so there’s always a balance to be kept between number of cores and single core performance…
My current live setup typically runs at less than 50% time load, even on my “smaller” i5 6-core DeskMini. And that holds also for fairly big and complex song setups. The power of desktop architecture 
…
Just some thoughts - not a definitive answer. YMMV…