Simon Reynolds has a great discussion of the Amen break used in junglism. And some interesting comments from a real producer, Brandon Ivers, about the techniques of producing breaks. These days it's apparently all about layering multiple breaks, using a lot of carefully planned eq and filtering to make sure they don't fight. This takes so much effort that the producer then isn't much into the kind of cutting up and messing about with the beat that characterized earlier jungle.
Seems a shame. But possibly why d'n'b got so boring. Though maybe I need to check out some recent stuff. Ivers says mashed up breaks are back.