Comment by Killswitch

Basically anything you can do in Node.js you can do in Io.js. It's nothing that really breaks backwards compatibility. The benefits of Io.js over Node.js is that it'll have a faster release cycle bringing in newer versions of V8 JavaScript Engine, allowing you to use newer features of that in your code.

In Node.js to use ES6 you would have to use the --harmony flag to enable them because the version of V8 that is used is so old. Whereas in Io.js anything V8 deems stable is available in Io.js without having to use the --harmony flag.