Coffeescript is just a short-hand for best practices javascript. It enhances readability and consciseness.

But nothing more. Bad (or neutral) practice is still possible in coffeescript. Mixing coffeescript and javascript files is easy. Classes can be defined any way you please (if you don't mind using something other than the "class" keyword).

I think the only reason for me to switch to something else from coffeescript is if some similar language where to get a nicer type system exactly right. I'm not holding my breath though.