Toe to heel edge to edge... a softer binding high back and baseplate are going to flex instead of pushing your energy into the board like a binding with a stiffer high back/baseplate.
I have ridden EST Cartels... more board flex as they are essentially baseless (well close enough for me). Toe to heel response was decent.
That's also going to depend on riding style - if you rely on your highbacks to put your heel edge down, you've got a different riding style than I do.
But that's an easy habit to pick up (call it good or bad), with the number of uber-stiff boots and forward-leaning highbacks on today's market. I'm personally glad to see the trend shifting away from that, back to softer boots and softer highbacks.
If you lift your toe-edge up by pressing your calf into your highback - then yes, I could see how a softer highback could be perceived to give you less edge-to-edge response. But for you lifelong skateboarders who ride more like a skateboard, letting your ankles actuate your board, and actually carving, you might appreciate a softer highback as a no-loss approach to getting that thing out of your way when jibbing around the park and trails.
Personally, I'd rather move the board around with my feet, that are directly connected to the riding surface - it's intuitive and much more direct than calves-against-highbacks-attached-to-bindings-via-highback-adjuster-lifts-toe-edge in my opinion. But everyone has different riding styles.