Originally Posted by AndrewX

Virtualmin (just as advanced, if not more advanced than cPanel) runs just fine on 512 MB with all the bells and whistles, I can even bring memory usage down to 256 MB with Apache and php-fcgi on a Debian virtual machine. That's with all LAMP services running, and enough modules to run Wordpress sites. That's difficult on Redhat or CentOS systems, and impossible to tweak with cPanel.

Also, cPanel compiles its own versions of software, the work required to apply patches to all of these custom compiled versions or to tweak them is immense and is usually performed by the operating system vendor (Microsoft, Red Hat etc). One of the results is a particularly poor security track record because the applications simply aren't patched as quickly or as methodically as they could/should be.

Both store configuration and log files in non standard locations. When you're dealing with very complex operating systems which administrators spend years learning how to use, this means, staring a Linux server upon which plesk/cpanel have been installed their years of experience is not worth nearly as much as it should be. This means problems are harder to find, harder fix, slower and more costly to resolve. Which of course makes diagnostics and support very difficult and outages are longer.