i recall the days when i was thrown into a project where the requirement was to use mootools, rather than jquery. even though they are both "javascript" in nature, it severely limited my productivity. i can see the same thing happening to companies trying out coffeescript, it may seem like you are doing the better thing long-term wise, but in reality, it is not so much. it's better to just stick to standards and you'll be more productive down the line, i can almost guarantee it.