I played with two rsync patches on some other distros last years. It appears these are not installed on Univention by default.
They are:
--time-limit
When this option is used rsync will stop after T minutes and exit. I think this option is useful when rsyncing a large amount of data during the night (non-busy hours), and then stopping when it is time for people to start using the network, during the day (busy hours).
--stop-at=y-m-dTh:m
This option allows you to specify at what time to stop rsync.
I see some useful value in these options. Are these options something you may consider adding by default going forward?