Interesting idea, but it is much more limiting than events and most of the behaviors would be ambiguous what they would do imo. The main tricky bit is it becomes harder to reference values you set in some levels of your node tree, since the tree is run in a way depending on what's connected. Events are simpler in that respect since they are run top down.
Well, out to in - if we as users can figure out multiple behaviours multiple controllers wouldn't be too complex either.
That said it could be an interesting tool to make complex motion equations, but probably not in C2. It would also need some designing to flesh out what nodes you could have and what they'd do. Behaviors for instance wouldn't work so well being put anywhere because they depend on the object itself.
I do like the concept, so I made a capx to play around with it.
Wow, I had an intention to make a visual demo to show the SPEED this gives you but you have gone one further - a working example! You also included right side inputs which I had omitted to keep things simple.
Now how anyone can say this isn't cool and easy is beyond me - a couple of clicks and you have complex movements that would take minutes to type in and that's if you have a perfect idea of what you already want.
Also - when you have behaviours if you remove one it'll wreck the entire system, all the events will disappear and good luck reworking that. In a system like R0J0 has shown here you just relink a couple of nodes and are good to go.
Input controllers could be introduced the only function of which is to provide values from events.
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It is great that this thread has at least spawned some discussion - one real hope for C3 would be an open system that lets you make plugins that make something like this possible and not just have a couple of values to awkwardly affect using events. C2 has many things that have been done to a little bit over the minimum - image editor, tilemap editor, even the UI of the event system (drag a subevent under the bottom event on the first try, I dare you). If nearly anything could be modified by plugins those problems would be a thing of the past.