[jfolkins]

I think it depends on what your objective is.

Strictly helping quanitfy technical and personnel risk? Grey all the way.

Getting the C-class to understand what a worst case scenario could be from a completely external threat. Black drops the most jaws.

Ultimately the later is a cultural hack. The absolutely hardest hack of all in my opinion. A way to get the herd moving in a different direction.

So it depends on what you are "hacking."