In reply to Derek Williams.

@Derek: You and I have already discussed these issues privately, so it's a bit naughty of you to publish them here in the hopes of attracting lots of "me, too!" responses from other users! Our new application cannot be backwards compatible with Finale and Sibelius, since the file formats of those applications are protected by copyright, and cannot legally be reverse-engineered. Our application will, however, support MusicXML as fully as is practical for both import and export, to try to create as good options for interoperability as possible between scoring applications.

Our application will also not be open source, which is a simple business decision that we have made. But we are not deaf to the concerns of users who are worried about putting their work into a proprietary application, and our application will contain not only good options for exporting files into other formats (graphical, audio, and semantic), but also a sufficiently sophisticated scripting API that it will be practical to develop exporters for other formats should they be required.