Some other thoughts:
- you can also backup to Dropbox (Google drive, Box etc.) If you have their app on your computer or device, when you backup or share, it should list as a location to save (export) to.
- I have tested over 11,000 songs without any problems importing again
- the song code file is similar to a text file so is quite small (you see it when you paste to forums) and reconstructs itself within the app on import
- if you are worried about losing songs, import from each device into iReal Pro on one as a master device then backup before you start deleting
- if you have the Mac version, it is much quicker to construct your playlists there (drag and drop). I often save individual playlists in dropbox and update each as necessary then have a composite backup for populating other devices for sync (as Bob suggested, Settings>erase all, then import the composite. Note that Settings like global transpose are reset to default so you will need to set these each time if necessary.)