There's a bit of a contradiction in your statement. MooTools is much more idiomatic than jQuery in it's use of javascript inheritance, object creation, etc, so it's "more javascript". jQuery is so efficient to work with because it created it's own nice DSL, not because it is standard. The standard could be C, would that make you more productive too?
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.
What damage? You can drop it at any minute and start working on the compiled javascript. I've done this a couple times.
That's true for any tool/language/platform/whatever, everything has a learning curve (and coffeescript's is quite short). Going by your words we shouldn't ever learn anything.
And you shouldn't switch to a language if your developers are not comfortable with it. Do some experiments, try it out on a smaller project, then you might switch if you see good results.
