I use Harmony Assistant as my main music tool, although I have a number of others with similar capabilities. I don't have access to full versions of Sibelius or Finale.

I would go along with much of the above. The manual doesn't always cover functionality terribly well: for example they introduced a feature fairly recently so that scores supported multiple views, but it didn't seem to be covered in the documentation anywhere.

Where the product does score well, though, is customer support. Over the years I've sent them maybe half a dozen bug fixes or enhancement requests and they have always responded by email within a day or so, and often these have been incorporated in a release within a month or so. I can only think of one, off-hand, that they rejected and that was to do with the ABC format where what they produce for triplets etc is technically correct but rather obscure; so obscure that some of the other ABC utilities can't cope.