As I understand it, BarFly is an ABC editor rather than a standard Notation editor. From your description, Jack, I would say that changing clef in noteworthy is no more complex. Essentially you replace the treble clef with a bass clef then move the notes to the correct position. It only seems more complex because leeneia gave a detailed "blow by blow" account which for someone who has not done it before, is very useful.

The transposition function in Noteworthy is a menu item and you simply select the the menu item and tell it how many semitones up or down you wish to go up to +/- one octave. Changing the clef automatically puts the notes in the right octave for midi playback, the adjustment of the notes after changing clef is to put them in the right position on the stave.

I would imagine top end notation editors such as Sibelius or Finale would take care of changing the note positions automatically but then you are paying almost twenty times as much for the full version.

I would say that as value for money, Noteworthy is almost unbeatable both for its capability for the price and for ease of use. I have tried open source editors such as MuseScore and NoteEdit and found both much more difficult to get started on, though I do know people who like them and they are free.