Hi Christian,
You only need to do backup of the databases listed in the SAP Note 1585981:
-> the SID database, because it is the database that contains your data
-> the Master, because it contains the main dataserver structure information (devices, databases, logins, roles, etc) and you cannot start an ASE without this database
-> the sybsystemprocs, because it contains the system stored procedures
-> the sybmgmtdb, because it is the Job Scheduler database
-> the saptools, because it is the DBA Cockpit database
The model is just a template, used when a new database is created, it doesn't contain relevant data.
And the temporary databases are recreated at ASE start. You are not supposed to store there data you would like permanent.
Regards,
Cris