[bshimmin]

I'm pretty sure not many people will understand what the word means in this context, and I would strongly suggest removing it. "valency" has specific meanings in chemistry and grammar, and I think it's not well-known outside of those contexts, and I'm not certain it really means what you want it to mean here.

That aside, this looks seriously awesome - the animation along the SVG path is great! The API also looks very pleasant.