The 21 Bitcoin computer is using Core, right? I can't find any information that says otherwise. Can someone please confirm this for me though?
I assumed so myself since the alternatives were not in a mature stage (technically and/or socially accepted) when 21 released their computer.
However, in their tutorial they do say that you will have a Bitcoin Core full node running at the end.
I was able to compile Bitcoin Classic from source and got it up and running with these steps: https://gist.github.com/redsquirrel/75b5192764b17c6ea265