I'm a long-time user of free/open source software, and write various things for both fun and profit. I don't take myself all that seriously and I do all of my own stunts.
You can find me at these fine establishments on the web: Open Source Musings, The Monday Kickoff, Weekly Musings. and The Plain Text Project.
Authored Comments
My daughter has started composing music for her high school music class with MuseScore. And since it can export to MusicXML, she can work on it in Sibelius (the proprietary tool her school uses). She likes it a lot more than she likes Sibelius!
You wrote that MuseScore can export to MusicXML. Can it import that format as well? And what other formats can it import?