The engine that Node is using is already in chrome, and iirc all the major current versions of browsers already have 97% support (tail call opts withstanding, I think for safari this is still a vNext issue).

You can use one of a number of modern targets which will avoid the need for the various polyfils etc... but if you need current safari and any IE support, you will at least need dual build paths, which isn't too bad. I kind of wish there was a babel preset that was meant to be used in conjuction with Financial Times' polyfill.io