I agree with @RiaanBadenhorst .
You still need the DPOO license to use the OST plugin.
The only good use case I have found is for Backup Exec.
With BE, it is possible to configure local opendedupe volume on the BE media server, plus config an OpenDedupe volume on cloud storage. You can then backup to local storage, then duplicate/replicate to cloud in dedupe format.
I have tested it - it works well.