Tried OCIS a while back and its way faster than NC syncing files, even the initial sync was so fast I didn’t trust it was fully done (but it was).
That being said, OCIS is missing several key features I daily use: namely proper DAV support (contacts, calendar, todo, journal, etc) as well as integrations for stuff like SeedVault for mobile backups.
Have you tried Synching? If you only need transferring files back and forth and no version control or snapshot-like backups, that might be even simpler