I have two homes and loads of audio gear at each. I regularly sync the homes.
You say “clients” — is it your goal to give a turn-key, professionally installed, set it and forget it type of feel? That’s likely not possible unless the entire digital audio footprint at each house is literally identical.
That’s because library restore does more than backup/restore/duplicate the library. It overwrites all of the configurations and settings.
It overwrites storage location settings, backup path settings, and audio endpoint settings (EVERYTHING, but those are the ones likely to be different at each location). It’s the audio endpoint settings being overwritten that is most problematic. Unless you have identical endpoints at each location (including computer and idevice names, desired dsp settings, everything) you’re going to have to repeat the setup and configuration of each endpoint after each restore. Grouping zones, the whole bit.
So your client would have two steps requiring significant Roon knowledge: (1) backup and restore, that can take an hour at house #2 before the music is available; then (2) repeat the whole endpoint and dsp configuration of Roon, including all displays.
It’s doable- I do it every Friday- but not turnkey or professional. Not what you want to saddle a client with. Better to get 2 licenses (so they work at both houses) and present them as separate systems that can occasionally be synced with some technical effort or by you.
IMHO, Roon is not ready for multi-house professional installation. Great experience once it’s working. But, for example, playlists, bookmarks, profiles and tags made at the second location will disappear when overwritten by a backup-restore from the primary location.
Better just to have your clients think of it as two entirely separate installs and don’t create the expectation they’ll be synched. Of course, you can still sync the music using a third party solution!
If on the other hand your client is a power user willing to roll up his or her sleeves and reconfigure at each backup/restore, it does work just fine.