Well, HT is totally right on the mark with that: "Most scores of standard rep operas suck." A lot of the pre-existing scans that are out there are are awful, with the exception on the ones on the Mozarteum site (
http://dme.mozarteum.at ) which are all Baerenreiter's. The ones on the Indidana database are okay visually but not always the most accurate ones. I definately see that as being the larger stumbling block and, unfortunately, not one I can do anything about (whereas the programing to read them and mark them up, is something that I can fix.) Most current PDF readers allow for coloured highlighting and for editing of the PDF. What I'm thinking about doing would be incorporating the touch screen aspect of things to a PDF reader/writer so that you could write in the scores (new notes, staging, etc.), only with a stylus instead of a pencil.
As for the other question: By and large the copyright isn't an issue. Most of scores out there are just re-hashes of scores that have been printed by the companies for dozens of years and have long ago passed into the public domain. Ricordi, for instance, really hasn't changed their scores since the second or third editions leading a 1898 Ricordi Boheme score to look pretty much like a 2009 Ricordi Boheme score. The only place that that doesn't apply would be in the case of translations which have typically been written more recently and might still be covered. For things like the Baerenreiter scores, most of the world outside the US, including Austria, still subscribe to Fair Use principles, allowing you to make copies to use, as long as you don't sell them. The basic license agreement is on the Mozarteum home page.
Thanks all for the feedback so far, in particularly again the issue about the various scores/score quality which I'd not though of ahead of time.
