WPMU Dev's software is incredible, because of its powerful customization options and compatibility with any theme. But that's not all...
There were two times where I needed their support assistance for some aspects of a plugin that their documentation didn't include, and they got back to me within a few hours each time. I was blown away by their service, as it was efficient, friendly, and concise.
I have not experienced this Apple-esque software quality and customer support in a very long time. I'm excited for my new and continual relationship with WPMU Dev.
You guys are on my list of Wordpress GOLD.