I’m not a fan of the “kitchen sick” approach, where these sort of features just get tacked in and over-complicate a node’s behavior. My philosophy is that one node should do one thing, and in general we try to stick to that. That being said, it is fairly straightforward to drop an invert node or a multiplication node and bundle them into a black-op to get this sort of functionality. It should be as simple as selecting the node in question, hitting ‘*’ then ‘f’, then selecting the three nodes and right-clicking and hitting [Blackop].
In the version of KCMs that will ship at SIGGRAPH, there will be little optimization. Currently there is not even constant folding. We are in the process of migrating our back-end to use the LLVM compiler tools (http://www.llvm.org) which will significantly improve the performance and optimization options available.