I'm very grateful to the authors of es6-module-transpiler - we've been using it in production for some time. But I ended up writing Esperanto anyway because the recent versions of es6-module-transpiler don't do one-to-one input-output mapping; instead it tries to resolve your entire dependency graph. We found that meant you can't use it with e.g. AMD modules in a separate vendor/ folder.

I've written some more about why to use Esperanto instead of the alternatives here: https://github.com/Rich-Harris/esperanto#why-not-use-existin...

Esperanto will have plugins for those build tools soon! Oh, and I second your recommendation for the Sublime JavaScriptNext package.