Thanks & that is great info - I'm looking forward to learning a bit more about Sforzando soon. I'm thinking my current problem may be a little more systemic, and I'm starting to think it's a bug.
If I import a song with MIDI tracks set for, say, the Piano and Bass, and I later assign real tracks to them, when I shut down and restart, the sample player re-appears in the first slot (under plug-ins in the mixer) and mutes the track. I can get rid of it easily enough by clicking on it, but it's a pain during a performance. I just wondered if there was something I was missing in the conversion, or an extra step I should be taking before reporting a bug to the support guys.