Wow, you really got this going, gents.
As is my chaotic custom I already moved beyond what the thread title may have suggested, After some consideration NUCs are out of the race - because of the limitations inherent to this particular platform and the noiiiizzzzze 
I moved on to the so-called “Mini PC” - sold on big A as “Slim PC”, and if I multiply the dimensions I count 15 litres holding capacity
Macbook, alas, is out of the race, too. The config I’d need (lots of RAM) amount to just a tad over 4.000 Euros, which is about double my budget for this.
This “Shuttle PC” is able to be driven by an Intel 10000 series CPU - not the top-of-the-line most recent machine but … well, it’s okay, I guess. Specs say 65 W max, so the “K” series with unlocked multi ceases to apply.
I feel I must add some clarification about what I intend to do with it … and maybe a teensy bit of background:
I’ve been “into” DAWs since Cubase 1,0 - Atari ST times, these were, and I LOVED those times. Before it was C64 and DIY MIDI interfaces on perfboard. I’ve almost always had a Cubase version on my “work computer” - even have been paying for it since version 6 - go figure.
And from time to time I tried to take this setup - the current synth in local off mode + current cheap USB audio interface + current Windows box or laptop - to the stage, even if the current Windows box was a full-blown tower and a U.G.E. screen (I need big screens for my bread job), keyboard, mouse and all.
I vividly remember one occasion this whole thing went pearshaped by myself placing the (at this time) laptop on top of the PA subwoofer. Where it froze and died 4, 5 songs into the set. Vibration? Electronmagnetic mayhem? I’ll never know. But, as I said, I always have “local on” as a fallback.
And I mostly do my thing (mostly tracking, arranging and a bit of lyrics-melodizing) at home on a stationary Windows machine with a separate de-bloated “Music” partition. Live gigs’ve been few and far between until recently when I started to notice a certain interest sprouting within myself to do the “stage thing” again, even in my advanced age and complacency.
So my “Live Rig” should be comfortable, hassle-free and powerful enough to give me the user experience I have at home on stage, too, i.e. enough power to play some of the more demanding sample libraries (something with “k” in the name) and soft synths (I just mention the brand name Arturia in passing).
I don’t earn money with my stage presences any more (never amounted to much anyway, there are so many gals and guys out there that earn a living doing it, and even if part of me envies those great players I can’t imagine this life for myself. My mobile and flexible days are long over). I have a full-time job that’s totally not music-related. So, though I’m sad to say it, you could say I’m a hobbyist now. Thus my budget. I won’t expect a ROI on this so I simply can’t afford to put a good month’s wage into a thing I need once a month if not less frequently. But I still DO jam, and I still get more or less regular “side jobs” as an arranger and contributor to various recording projects.
Home Rig: RME HDSP 9632 in a i7/z97/64 GB RAM machine - almost a decade old but still alright for my needs.
I can forget about the RME card btw. - nobody does mainboards with PCI slots any more, so I bought the ESI MAYA44 card (150 Euros, by the way) that will do the job on stage, I suspect.
After this rather long and rather personal digression:
I need a smooth, mostly error-free setup. I would prefer MacOS because of its native digital music capability and the good build quality but there ya go. It just gotta be as smooth as the home machine and far less cumbersome, transport-wise.
As many have said, it just depends on your own personal situation and what you want to do. It is amazing what can be had in small packages these days,
