I like Erlang, but in shops I've worked with that have your "average" dev in it, it's syntax and semantics would be something they struggle with (if it ain't PHP, they'll struggle with it...). Unfortunately I don't blame them. That said, I think if they truly needed to build a somewhat stateful concurrent router, Erlang is a better choice (solely because it's battle tested in those highly concurrent workloads). Picking tech for big things like this when you have to balance a teams knowledge with the right tool is a hard problem in my experience.