Can I sync my databases between DEVONthink 3 and 4?

Yes, you can sync your databases between DEVONthink 4 and the older generations, DEVONthink 3 and DEVONthink To Go 3. Audit-proof databases are only available in DEVONthink 4 and cannot be synced to DEVONthink 3 and DEVONthink To Go 3.