DMCS was pretty decent as standard notation software, but in fact it focused more on typesetting than playing; though I've used to compose. Then, I've used Bars&Pipes Professional, so I could export to MIDI and friends (without Amiga… Amigans were rare) could listen to my compositions.
OctaMED was great!
Old style trackers do exist for modern computers too (Windows and Linux, and Mac too, I suppose). I haven't ever used Renoise, but I know friends who love it. I sometimes play with Puredata and Csound, powerful tools even if not too much userfriendly.