After reading the article, I went into their IRC chan to post this question (i.e. are they leveraging all the research from really-smart(TM) PhD's at Microsoft Research & production testing that Rx has behind it).
This guy has a doctorate, so I'd imagine there was a reason why RxJS wasn't leveraged, especially since it seems like a natural fit especially with Typed.*. And n general the Elm/Haskell community is way less fan-boi-trendy-node-js-macbooks-Rails-flavor-of-the-wheel guys who will nay-nay anything that is Microsoft.
I'd love to make the Elm jump, but it still has the Haskell stigma (not enough engineers making hiring difficult, too 'academic', etc) where my clients (enterprise) won't let me dev with it. They do however let F# in some projects. MS should do what they did for OCaml -> F#, but for Elm -> something_I_can_say_is_first_party_MS_supported.