> because every script compiled with every version of CoffeeScript is compatible with every other version, we're much more comfortable making changes to the language than we otherwise would be.

This attitude concerns me. I can't just say "oh, that's CoffeeScript 1.0 stuff, just trash it, the JS still works". I still have to update the CoffeeScript to upgrade the version. There's no less risk in breaking backwards compat with CoffeeScript than any other language.