implements the user database via php/mysql.
mysql ?! Overkill would not be an understatement here. I will not even bother to explain why it is wrong. Install mysql for list of users ?
but it shows that such a user-management is possible without even changeing the core of the p2p-application.
You did not read anything I wrote, didn't you ?
the file-permission problem (that doesn't apply to me) is solved in this extension by not giving direct access to the incoming folder
You missed the point again.
Ok, I will emphasize my point: you can't ask users to install php and/or mysql (please, no discussion about it). So, file ownership _should_ be maintained
in the amule core. And propagated to any remote control interface amule have: remote gui, webserver, amulecmd.