it was a point that even if you are merely switching a js framework where both are written in javascript, productivity can drop.

if you now switch to coffeescript, something not remotely close to javascript or any other languages fwiw, you'll experience un-productivity. it's akin to having your top developers walking in eggshells and doing nearly nothing close to what he is capable of.

i think coffeescript is great in the sense that we are trying to create a better language. but i also sense how much damage it can bring to budding startups who can't find talented coffeescript'ers to fill the void when their lead developer moves on to other things.

a one off go project, i'd say it's fine. but anything more complex, i think you'll see programmers wishing they had gone back to what they were familiar with.