I disagree and my original statement applies as much to TypeScript as it does to an ECMAScript 6 transpiler. If you want to use the new features and you're transpiling now you need to have a good understanding of the differences between ECMAScript 5 and 6 and you open yourself up to possible bugs in the transpiler.
Instead you could just write ECMAScript 5 until 6 is more widely available. Sure no one likes to wait but it requires the least amount of expertise and lower chance of bugs from a 3rd party interfering with your application.