As, unfortunately the command line interface fmadmin can only launch schedules asynchronously (which is bad), meaning that the schedules is launched in the background, and you don't know when it's finished, it's currently impossible to manipulated backups from the command line : you can't launch a backup, wait for it to finish, and then do stuff on the backuped files, like moving them in another location or more importantly compressing them
So rather than asking to have compressed backups (which would task FMS CPU ressources), I'm advocating to just have a simple new addition : a new schedule type, that would just allow the backups to be followed by a system-level script. I think it would be relatively easy for FMI to implement this, since the run system-level script code is already there.
Moreover, it would be much more useful than just having compressed backups (which would task the CPU), one could copy the just finished backup to another machine that would do the compression and archive it, and maybe sent it in the cloud.
And I'm sure it will be perfect with FMS cloud by the way, so a little bit of code for huge possibilities