Oracle 11g is best in this situation. coz when you creating the data guard environment, you can enable flashback on both primary and standby. Its really a cool feature. In 11g the standby database is also called active standby database, coz you can read the database(ie, you can query using select statement) and at same time log shipping also will occur. If you want to insert in production database, you use open the standby database in read write mode. which turns on the flashback database feature, and when all your insert operation has done and when you convert it again to active standby, all your dml will be flashed back and the logs will started applying. But 10g lacks this feature.