i just upgraded from 0.9.5 to 1.0.1 with preaparing by combine "db.inc.php" and "main.inc.php" into "defaults.inc.php" and made the db-scheme changes before rollout

• my self built RPM only provides the classic theme
• no configuration files in the RPM
• upgrade completly un-noticeable
• $rcmail_config['session_storage'] = 'php'; out of the box

frankly, even my existing user session did not get interrupted - impressive!