SyncPad switched its webclient from JS to CoffeeScript.
In terms of human-readable code, we reduced the lines of code by ~30%. It's cleaner and more concise. I feel our code is more managable because of CoffeeScript.
In terms of the generated JS, I really appreciate that CoffeeScript creates an abstraction that will implement JS best practices and consistency
At this point, any JS work I do is done with CoffeeScript