I have a DMA with this database configuration : (both external databases)
If I want to take a backup of this DMA and choose 'Full backup without database', will I be able to restore that backup file on a new DMA and not lose any information present in the databases ?
You should not lose any data as long as you do not touch the database.
If you deleted an element and the backup restore makes it so the element is restored, you might lose some element data like username and password configuration.
Trend data and alarm data should still be available for the element.