The main difference is & channel mode for OctaMED no? Unless Pro-Tracker was updated for that too after I stopped using it at the time Amiga was alive and well. The rest is really down to personal preference, try out both and see which you like.
There was also Startracker which was Pro/Noise-Tracker with 8 channel sound too I believe.
And yes best to start with an Amiga if you only want to create MODs for other Amiga users, saves a lot of hassle with chipram shuffling for samples later and you can hear the samples on an Amiga which is important.
Do you intend to bash the keys on the computer keyboard or do you want to go all professional and record the tunes played on a MIDI keyboard?
