What are the specific problems that you're looking to solve with ES6? Promises are weird when you actually get into them, and async/await is still a ways off from real support. Iterators/yield are awesome, but support in browsers is missing (Except for FF). The other stuff is... nice? I guess? But not real problems that can't be solved in a nice functional way with ES5 code.

Why use a new tool that is still changing when an old tool that is very well tested still works great?