afaik mocp is it's own daemonized process, so you can close the client and the music keeps on playing; cmus is a standalone client that just reads from the file

afaik mocp is it's own daemonized process, so you can close the client and the music keeps on playing; cmus is a standalone client that just reads from the filesystem and URLs and does not daemonize. cmus unfortunately skips and segfaults at times on the latest Debian packaged version, which is of course a few versions back (2.5.0 vs 2.7.0 iirc) and so I'm relying on mocp much more now. To answer your question more directly, again afaik, mocp is not accessible over MPD (separate daemon altogether) and does not play nicely with Spotify, but I'm not a user, so wouldn't know. Neither is mocp accessible over the network (afaik!).