We can offer Plesk and support issues within Plesk but it wouldn't be Managed. You'd need to maintain your own backups and restore them if there was a HDD failure for example. You'd need to keep the Plesk software updated too. Any questions let us know.
I see all your Managed Dedicated Server only has CPanel as the Control Panel and under the additional options you also don't list Plesk. Is Plesk with one of your Managed Dedicated Servers an option? [Broken External Image]:http://www.1-imageshack.us/images/images/45.gif