Relays did suck. Shadow fit is money and I endorse it.
Hinge is not Shadow Fit. The Hinge is similar to Shadow fit in what it does, but Shadow fit is completely different than the Hinge in what it does.
The Hinge gives just a bit so you can get just a hair more leverage over your tip providing a more skate like pop. Shadow fit also gives a more skate like pop, but also improves board feel and gives a completely new feel to a binding. Both do what they're supposed to do and do it well.