Update 13 Nov 2012: Patch 14726136 has been obsoleted. The note on MOS indicated that the patch caused some metrics to be calculated incorrectly. The patch has been replaced by patch 14833587. I have applied the new patch and all appears well — jobs are running and redo generation on the repository database remains where it was before the upgrade to EM12c R2.
Following up again on the EM12cR2 upgrade issue from BP1 that causes significantly increased redo logging on the repository database due to heavy insert activity in EM_JOB_METRICS. I first covered this here, with a followup here, a partial workaround here, and then a warning here.
Patch 14726136 has been re-released on MOS. The initial release caused problems for me as it prevented all OEM scheduled jobs from running, eventually causing me to rollback the patch. I am very pleased to report that the new update of the patch (from Oct 30th) applies cleanly and all of my jobs are now running on-schedule and completing successfully. EM_JOB_METRICS is showing no more than 11 inserts per second, and more than a minute is passing between the batches of inserts. My redo volume is already down significantly.
Big thanks to Oracle support and development and the EM12c team!
Pardy DBA 
U truly created a lot of outstanding tips with your blog, “Final
(!) update/fix for EM12c increased redo from EM_JOB_METRICS
after upgrade to R2 (bug/patch 14726136) | Pardy
DBA”. I’ll become returning to your blog eventually. Thx ,Adam