Looking at the subframe bushings, there is a lot of empty space above and below them. (I don't know what keeps the subframe in the middle of the travel range in fact!) That space allows the rear subframe to wiggle pretty freely. In turns, the back end has that much more (nearly) unsprung play in it.
If you want good handling (and have an even remote desire to tune it) you want the springs to control the return force as much as possible. That means stiffening bushings so they are stiffer than the springs. These air gaps are a good place to start.
For the record, I have the 2-piece over-and-under bushings and I still get wheel hop in some situations. But much more seldom than before.
