Am I correct in understanding that a ViewSet is mainly useful when connecting to multiple different repositories?
Yes, we introduced the explicit notion of a CDOViewSet when we supported external references in the framework, i.e. references from one repository to another repository or completely different resource types. Each EMF RescourceSet always has an associated CDOViewSet (when used with CDO) but in the standard case this ViewSet will contain only a single CDO view or transaction.
