As a lurker on this thread since the beginning I finally have a question to pose to everyone. @Fehlindra noted that on snow skis there is one foot per ski, which drives boot and ski design. Slalom water skiing has both feet on a single ski, so are we dealing with issues more akin to snowboards? I know we stand facing forwards vs sideways, but the two-feet/one-ski analogy is there. And snowboards in general have very flexible bindings especially when compared to snow skis.
I'm not nearly the level skier of many here, but what I like on a binding setup is for my foot to feel locked down, but not my leg. Ideally I'd like my feet to be bolted to the ski but my ankles allowed to flex so I can pressure the ski appropriately. I've been considering trying a hard shell this next summer to see how it feels. As others have said, I like to be "down" on the ski. HO bindings in the '90s lifted you up off the ski by a 1/2" or more and I hated how that felt. Get me down "into" the ski as much as possible. Personal preference I suppose.