Hello Arlo, one thing who could be great is an option to export/import setlist, I mean the order of songs in "show/modify songs". A simple file to export from this screen, and to import on SLM installed on another tablet.
A set list is a collection of songs, so exporting a set list wouldn't be useful if the other device didn't have the same songs. However, you can export a whole database, which would include the set lists, songs, and smaller elements like set names, tags, custom fields, etc:
http://www.arlomedia.com/apps/setlistmaker/tutorials/export_import_databases.html
It could maybe useful then to get the possibility to import exactly what we need from an exported database. Songs, Playlist, midi presets etc. Because the songs of my singer are not edited like mine, I've only got few lyrics for 2nd voice, I've got midi presets which he doesn't have etc etc.
It would be very complicated and probably lead to lots of "mistakes" to try and import and export portions of databases or merge databases. Your situation would work well in BandHelper, where users can enter personal versions of lyrics, and where you can assign MIDI presets to individual users:
http://www.bandhelper.com/main/SLM_comparison.html