While mentioning other tech, I have found Scala.js with Scala.Rx [1], ScalaTags [2], and some glue [3] a great way to actually do reactive DOM updates based on state change. I find this way cleaner than building and diffing entire DOM trees (even if they are just AST's in JS). Mixed with ScalaCSS [4] you have a nice type safe solution.

1 - https://github.com/lihaoyi/scala.rx 2 - https://github.com/lihaoyi/scalatags 3 - https://github.com/rtimush/scalatags-rx 4 - https://github.com/japgolly/scalacss/

I love elm, though even the author has stated that for the moment it is more of an experiment than anything else, until they can work out an elegant way to do data modelling (i.e. server communication).