Both modes are enabled by default. Cookie mode based use is controlled by the presence of the cookie control in th search request. Otherwise draft mode format is returned.
Changes are available in cn=changelog as long as the replication is enabled on oud. Note that you might have to explicitely add some acis to allow access to changelog records (by default admin rights required)
It is also possible to explicitely enable changelog for a standalone oud for testing purpose if needed.
Sun Identity Manager supports draft mode only.
New applications being developped will take advantage of the cookie mode as it has significant benefits over draft mode.