We are a web development agency. In the past we've developed on Joomla, Wordpress and Drupal however we're becoming more Wordpress focused. We have systems such as InfiniteWP that we use to manage multiple sites with Wordpress installations and keep them up to date. This works really well for us as we can collect maintenance fees from our clients to keep plugins up to date and we can use a single admin login to be able to login to any of our WordPress sites.
I'm looking for a similar system for Drupal and as yet I haven't bee able to find a solution that offers me the same benefits as I can get with the other CMSs. At the moment, it's really only the one thing that's holding us back from dedicating more development resource to Drupal. Can anyone offer advice on a similar solution or how other companies are managing this issue.