Some of the most common requests I get for ControlPlane involve more elaborate rule and context systems. Requests for negative or NOT rules and context groups are not going unheard but you can certainly voice your opinion over on Github. The more feedback I get about how these two key features should work is very important.
These features are currently being looked at for the rewrite of ControlPlane. Due to the current architecture of ControlPlane these features are difficult to implement without breaking the existing configuration system so it is very unlikely they’ll be seen in the 1.x series of ControlPlane.