> leaky and half-featured classes.

This is a common willful misconception. CoffeeScript classes are isomorphic to JavaScript prototypes -- the do precisely the same thing. In addition, there is a shorthand syntax for prototyping objects, if that's more your style:

    Dog = -> 
      ...
       
    Dog::bark = -> 
      ...

    Dog::run = ->
      ...

Note that the above will produce the same result as:

    class Dog
      bark: ->
        ...
      run: ->
        ...