Duncan - Not using Storage groups/SDRS was the conclusion I was reaching just before you posted..
With the EMC recommendation to not enable automatic movement (which in my mind is one of the benefits of SDRS), and the issues with SRM not being able to dismount the datastore, I'll hold off for now.
Hopefully, as time goes by, some of those issues can be resolved and I'll revisit usign the storage groups.
Thanks for all the comments.
Mike O.