Hi, I had a need to move twice so first time I've just compressed www and copied on new server with ispconfig and recreated pages. Dunno why but I had troubles with server after doing that. Server would randomly crash. Anyway then I moved to another server but this time I've rsynced almost everything. Problem is I've already installed ispconfig with tutorial and then moved all data. That caused some trouble with cron, mysql, and user accounts but it was all fixable (config files or passwords were wrong) and it's working now without a problem, So rsync worked for me great. Anyway what failed is ssh logins, dunno why but whatever I did, I was unable to login to new server so I had to delete and create again ssh account for all users.
ISPConfig -> the best open source control panel