Is it unwise to start a large, new project with CoffeeScript?

I know it's grown out of fashion, but I still really like CoffeeScript. ECMA 6 is great at all, but ECMA 6 + CoffeeScript seems even better. I'm sick of braces and semicolons if I don't need them.

I avoid the more syntactically ambiguous parts and try to use sensible whitespace.

Would it a bad idea to embark on a new, large project using 100% CoffeeScript instead of Javascript? Are there any other JS transpilers with a Python/Ruby-ish syntax that would be recommended over it? Should I stop caring so much about syntax sugar?