Given that Mocha appears considerably more complicated than the built in trackers (plus the added expense), it may help to make more of case regarding what Mocha can do that built in tracking can not.
Maybe this is an example? I've become quite comfortable with the built in tracking and find it quite useful. The up/down and rotate features seem to work quite well, but the scale feature is pretty problematic. I typically record the scale, but then often delete those keyframes when the scale starts bounding up and down (not scaling smoothly). Is scaling perhaps an example of where Mocha is superior?