I'm actually getting some use out of Intensity right out of the box. I'm working on a VERY heavy track and I've got a zillion layers of ultra-heavy chug guitars with some 16th note synth pulses and acid 303's on top. Intensity is working well on a couple of individual tracks to make them "pop" more (not "more pop"). Since all of the chug guitars are recorded wet and not re-amped, I can't go back and adjust amp settings - but I can throw Intensity on a couple of the layers to make them "spike" more. So far it's working well on a couple of guitar layers and on one or two of the synths, especially the 303's which, even when distorted, are a pretty small sound when compared to the stacks of mega-guitars.
Putting it on a whole stem was too much on this mix though. I need the sine-wave-ish component of the bottom of the gtr+bass stem and the drum stem to stay clean and clear and Intensity was screwing with that when it was set to spike the guitars, but on individual elements it's all good.