If you know Haskell, then the remaining bits of PureScript will not take very long. It's like moving from C++ to Java, or Ruby to Python. Most of your experience carries over, and you can learn the differences as they arise. You can likely be productive in PureScript tomorrow.
In my experience, PureScript has been much nicer to work with than GHCJS or Elm. PureScript's editor tooling is absolutely fantastic, and the language has "fixed" a number of warts in Haskell. The record system and interop with JavaScript are wonderful, as well.