Can I ask what you compare it with when you say amazing? I too liked it a lot but don't know what the state of the art is elsewhere.

Pardon me for wading through your history but you seem to have used Buckle script too- and claim that it has insane compilation speed and tiny Js size - (which would translate to a one time perf gain in download/parse/exec). How is the performance difference over the course of application? Would you still use Scala.Js if you didn't use Scala on the back end?

Also, why not create multiple scala-Js projects to do what you're looking to do? You'll have to fight SBT but if you die you're a martyr and if you survive you get to fight it another day...