I am still trying to push through the upgrade, but at this point it looks like the main stumbling block is acs-authentication. There are too many changes from 4.6.x infrastructure, that make an upgrade *extremly* difficult. Running upgrade scripts that update data model, etc. is not enough -- there needs to be an upgrade script that properly updates users, auth_authority and friends. Without that it is, basically, impossible to login to the installation to perform upgrade of th rest of the system.
