chrome/ff dev tools have source maps support, I can work directly with coffee source the same way, as I work with less source instead of compiled css ... only coffeeconsole is in a separate tab via chrome extension
+1, CS can be learned in few hours and any questions on what each constuct produces can be quickly resolved in coffeeconsole for chrome
Verification: lead development of 50MD and 300MD mobile html5 apps for major UK TV's and even people who did see CS first time were able to pick it up quickly. I had literally about 5 cases when I had to answer some chat questions on how CS works, and about the same count when I corrected/optimized some CS usage in a code review.
The productivity gain was impressive. In ducktyping, but esp. in __understanding__ the code quickly.