There does seem to be an issue here. Yes, perhaps the " Mass Storage Mode" might be a good way to copy exact files and folder structure, and maybe when the message of too many files or folders pop up, but won't solve the issue.
The whole point of User Backup is to save or backup one's User data. If you were to have over 1.9 GB of data on the Genos User Drive, then according to the Genos manual, you cannot make a user backup file.
The User area on the Tyros 5 was very small, I think I recall around 130 MB, but adequate for file edits or creator edits you are working on at the time. All saves by default were directed to the User Drive. Also any custom user VH saves, MIDI template saves, Audio Style saves, custom voice user saves or DSP user saves. These User saves were very fairly small files and I found that roughly 100 Audio Style saves (from style creator edits) could fit in the Tyros 5 User Drive.
So basically I only used the Tyros 5 User Drive for Audio Style saves, however User backup was handy because all my User files, like MIDI template and other custom user files could be saved in a single backup file and copied to my second Tyros 5 board. This way I didn't need to recreate all my custom user data files, user MIDI templates and others. When the backup file is created it usually warns the user that Audio files and audio styles cannot be saved.
So if I wanted to copy the similar single User Backup file save from one Genos to transfer to another Genos keyboard, the User Drive data cannot exceed 1.9 GBs, yet the User Drive had a total capacity of 58 GB. So in order to make a backup file, the majority of the User Drive capacity is a total waste.
Maybe I might have to rethink and use the hidden underneath USB after all (equivalent to the Tyros 5 HD), for all my files and use the Genos User Drive pretty much as I did on my Tyros 5, for current edits or creator saves and the various custon User saves. Seems to me that Yamaha needs to explain the 1.9 GB limitation, intended purpose of the User Drive, and the point of having a 58 GB User drive capacity yet User backups cannot be made when 1.9 GB is exceeded.
Marcus