If your users have full control over their sites, it would be wise to impress upon them that the GPL is not there to be abused, and that they also need to respect the copyright and credits and not obscure or remove them in any way.
Failing that, you could end up with your DNS being blacklisted here, because we don't support anyone who breaches the GPL and the license conditions of Icy Phoenix.
:lcop:
Some functions like footlink settings in the ACP i deaktivated for this reason and they have no ftp acces so they cant remove the copyrights ;)