Just to close this issue.I ended up escalating this to B&R team at oracle and the answers given to us where reversed. The facts are ...
1) using rman, no need to stop MRP prior to backup (backup sets or image copies). 8i is an exception.
2) User managed backups e.g. 'cp' require a shutdown of db or MRP. 2) an rman backup on an RO open standby db is valid. 3) Active DG is supported in rdbms >= 11gR1 Hope this helps Thank you. -- //www.freelists.org/webpage/oracle-l