If you're adopting ES6 into your stack, you may as well go all the way and support ES2017 features.
If you stick to ES2015 features that Node 6/7 support, you can skip transpilation node-side though. Depending on the project, that can be quite convenient.
I always felt transpiling on server side as unnecessary overheard, Node 6/7 support most of new features it's too much to transpile for 1-2 features.
Any good reference for ES2017 ? I believe the documentation is still lacking.