Plesk is very finicky about the versions of software you install and very jealous of its own configuration file. So, once a server is running Plesk, it controls everything from Apache to MySQL to PHP. You can't modify a setting in Apache. Plesk will roll it back for you in few minutes. This means tuning things on a Plesk server is a pain. It also means you cannot upgrade things from RPMs, ...etc. While the motivation behind this is understandable (they own the configuration, so they only install their own sanctioned versions of the software and disallow you from changing it), it makes life so much harder if you want to upgrade something or install an accelerator, or tune something. So, this "fun" way will now extend to Drupal? Great. Means more headaches for the clients and consultants.