Open Stack

With the pending release of Essex, I'm making plans to upgrade our internal cloud infrastructure.  My question is what will be the best approach?

Our cloud is being used to support internal research activities and thus needs to be 'relatively' stable, however as new features become available (major features), it would be nice to be able to role them into our operational cloud relatively painlessly (wishful thinking perhaps).

My question is, should I base our new installation directly off the Essex branch in the git repository, or use the packages that will be deployed as part of the associated Ubuntu 12.04LTS release?  With Diablo, I was forced to use packages from the ManagedIT PPA with additional Keystone patches to get a consistent, stable platform up and running.  Obviously, some of these problems were due to confusion caused by various documents describing different incarnations of Openstack, and not really knowing what was current and stable.  Especially the packages shipped with Ubuntu made assumptions about how Openstack was to be deployed that wasn't really apparent.

Just wondering.  Any thoughts appreciated.

Regards,
Ross