We have been using EA's API ProjectTransfer function to do a backup of our projects automatically (we have some projects on the filesystem as well as one project in a DBMS)
However there are some caveats to this function: We cannot run our scripts unattended(as a task running daily). Meaning the user has to be logged on for the script to run since EA cannot be run unattended. Also, we have noticed a bug in which the Accept Windows Authentication option does not carry with a Project transfer.
This is why we decided to move our scripts to simply copying the files for backup. (And rely on the dbms team for backing up the DBMS repository)
Should we be simply copying the files for backing up the projects? Or is there something important ProjectTransfer is doing?
No, there is no added value. As long as you do a file copy. The project transfer is more meant on a RDBMS-EAP level which can not simply be done with a file copy. For RDBMS-transfers with the same database type you can/should also use database backups as transfer method.