If there is a large user base at a remote location that will be manipulating files, then you should consider what remote sites are required.
What do you want to replicate?
The answer depends on the remote user community you are going to support. You need to consider the time to view remotely versus the overhead of replicating large amounts of data. If for example, the remote site only views one type of documents/files, you can configure your vaults such that all the files for the remote location are in one vault location, and you can be very selective on the vault folders to replicate.
What replication software to use?
SmartPlant Foundation does not have built-in file replication. Depending on the complexities/volumes of data being replicated, you might use something as simple as Robocopy or consider some third-party replication software that is designed to build replication rules for copying across a WAN.