Thanks for the response, it seems that your use case is very similar to mine (Ruby, Node.js, etc.). I actually decided to go with the i3 model with 16GB of RAM, since I don't think that I will do anything extremely demanding or graphically intense and it's super affordable to boot. I'll run elementary OS or Fedora on it, hopefully it will all work out.
As long as you have no plans to play games, it's a wonderful machine for development. It's really fast for its small size, noticeably faster than the Macs I'd been using before. I spend most of my time with the NUC doing Ruby development in Fedora, with some Clojure and Node.js on the side. I've done some office type stuff with LibreOffice. I've dabbled in OpenSCAD while working on a 3D print. The NUC is more than enough power for all of that. I haven't played with Windows 10 too much, but it's also snappy when I need to boot into it.
It's a very quiet machine. On full blast, you might get a blowing sound similar to a stressed MBP. But usually in normal usage it's no more than a low hum; I can't even hear it unless I listen for it. You can throttle down the processors in the BIOS to make it nearly (totally?) silent if you like.
The most annoying thing about the NUC was installing the BIOS updates before getting started. The NUC6i5SYH had a lot of problems at launch that needed to be patched. Once I got beyond that, everything was smooth. The NUC is basically a laptop board shoved into a small box instead. If the things you want to do are possible on a laptop, they'll be possible on the NUC no problem.