Hi,
EMS does not have the notion of a MediaCache. It has something better: multiple media storage capabilities along with detailed information for each and every played file (metadata, how many times was accessed, last access time, etc), including remote locations (boils down to mount a remote fs)
Having this info, creating file replications can be as easy as writing a simple shell script running in cron. Yes, is not working out of the box just yet, but it offers a lot more flexibility. For example, you can declare one of the media storages as a fast storage (possibly SSD) and have the cron script keep all the most wanted files on it, dynamically updating the list.
Please let us know if you have more questions about the media storage capabilities.
Best regards,
Andrei