Just to add to my post, open source is great isn't it? We live in a great time. OS is the great equalizer. How else can a single guy create something, say jQuery or CoffeeScript, which decimates other work by large teams, whether open or close.
So today Microsoft added yet ANOTHER transpiler. Great. News at 9. You see, in this new world, the fact that it's Microsoft, or Google, or Apple or anyone, means nothing.