navaho is correct about cpanel.. as since the backend essentially automates everything, the software itself has it's hands in a lot of aspects of the machine. As a general rule, do your research before making a decision. Try out as many demos as you can, as trying to switch systems can be quite a task.
I'm not as familiar with Ensim, but I know cpanel does allow a bit of freedom when it comes to installing server software. For example you can install mysql, php, various perl modules, programs like imagemagick, etc etc all manually, without the need of the control panel. So if you don't want to use the backend to do the updates for you, you can compile and install pieces as you see fit.
