OK; so I dug into the SSH identity issue in more detail and its related to the removal of /var/lib/waagent on upgrade/reconfiguration.
The Pre-Depends/data-saver fix negates this problem and the SSH keys stay intact.
I did notice that the new package installs an upstart configuration with a different name to the old one; so now that we don't waagent --uninstall on upgrade this needs to be stopped and removed manually to ensure the new configuration and agent can start correctly.
OK; so I dug into the SSH identity issue in more detail and its related to the removal of /var/lib/waagent on upgrade/ reconfiguration .
The Pre-Depends/ data-saver fix negates this problem and the SSH keys stay intact.
I did notice that the new package installs an upstart configuration with a different name to the old one; so now that we don't waagent --uninstall on upgrade this needs to be stopped and removed manually to ensure the new configuration and agent can start correctly.