I think you are misunderstanding why people call the shiver stiff. It is laterally stiff, but has progressive travel. Meaning the top of the travel is plush for high speed downhill and the bottom of the travel stiffens up so you don't bottom it out.
Sounds like you don't know how to pick your fork. That is EXACTLY how that fork should perform at your weight. Look to xc forks if you want forks that are more linear. Marzocchi dj forks are also stiffer at the top of the travel to feel more rigid like.
Comparing the flow to the shiver is like comparing a ferrari to a ford hatchback. They aren't anywhere near the same quality ride.