Is there any function that allows export of the song DB to a csv file? If not can one be added?
No. Why would you want to do this?
This feature would help with backups and using the data with other applications. For example, I'd like to try an alternate setup using MainStage but I fear I'll need to rekey everything again. Thanks for listening.
There are already two systems in place for backing up the app data, so I don't think a third system is needed to do that.
For importing into another app, Set List Maker doesn't offer this, but BandHelper can export songs, MIDI presets, events and transactions from its web interface:
http://www.bandhelper.com/main/SLM_comparison.html