[first cut: 5 October, 2013].
CoffeeScript enthusiasts want to be productive - amen to that - but calling the skeptics names undoes any goodwill your enthusiasm should generate.
I think CoffeeScript is fine for driving tests, but in a high-performance application – which is "equivalent to the concatenation of its source files", Justin Searls, http://blog.testdouble.com/posts/2013-06-16-unrequired-love.html – you need to watch for bloat, and CoffeeScript (along with the CSS preprocessors) re-introduces that in subtle ways that should be acknowledged.
Debugging and tracing generated JavaScript in the browser requires source maps, so you can use Chrome DevTools, e.g. Relying on those tools is a small part of the cycle, with some potentially exciting gains (live reload in the browser, holy mackerel), but it introduces a hard dependency in the tool chain, rather than being tool-agnostic.
The Class implementation in the CoffeeScript interpreter is less than optimal. The boilerplate is repeated