I tested both pending versions with our buildout, with a fresh bobtemplates.plone-package as well as with a big project currently on 5.0.6 and all seemed fine.
The only issue is could find at first glance was that the new actions-controlpanel was not added to overview-controlpanel when migrating from 5.0.7 to 5.1b1. It was added when creating a new site though. There might be a upgrade-step missing.