reqmaster: not necessarily a good idea. Problems with firewalls, with packet losses (mastership in the packet), with scalability (i.e. volability). See also: CMA03.
Request for partial vob replication: as such, the answer is no. Now, there were convincing cases, with sub-contracting, company mergers and out-sourcing, customer specific variants etc.
export restrictions, branch exclusion shared mastership: no admin vob lstype -obs