I consider myself a decent java/web developer. In my career I have always used servlets and ejb's with a web front end, most recently incoporating jquery and ajax.

I can see the theoretical benefit of using GWT or Vaadin: it is my understanding they convert Java code to the required JavaScript/HTML. So the developer gets the benefit of cross browser compatibility and compile time error checking (of web GUI elements).

My question is threefold:

1. Are there any other benefits I am missing that would be gained using Vaadin or GWT?
2. I am actually quite confident and productive using HTML and JavaScript - so will I actually see any benefit? Or will it just make my knowledge of these areas redundant (as they are handled by GWT/Vaadin)?
3. Will the end result be that I can create enterprise scale data driven websites in a reasonably short time? I can however already do this, and I have not wasted any time learning GWT/Vaadin.