Other than some of the weird licensing I've heard (by know very little) about, I love so much about ARM / RISC based systems but the one thing I find myself needing is higher single core clock speeds, not just on ARM but on x86 as well. Considering how popular and accessible interpreted languages such as Python are these days and yet how hard it is to write multithread code easily I often find processes bottlenecked by a single core, I'd love a high clock speed (3.5ghz+) dual (or more) CPU ARM setup with at least 24 physical cores and a sensible amount of L1/2 cache, but as far as I'm aware it's not really something that's readily available. Something like that would hum with modern Python / Ruby apps or even an ARM build of PostgreSQL and a modern (4.10+) kernel with NVMe storage (if that exists / makes sense for ARM) running either CentOS 7 + some trusted third party mirrors such as elrepo/epel or Fedora Server which I have not actually tried in a production environment so I can't comment on its updates stability but have found it the most reliable desktop desktop distro (excluding macOS).