The links you pasted show Firefox currently being 3x faster than Chrome when running asm.js code, so I'm not sure what your point is. V8 is good at generating fast code without the hints, but obviously the extra restrictions help the optimizer. Even Google admits this when they try to promote Dart.

asm.js does little for you if you write "real JS", but this thread is about cross-compiling other languages, which clearly has real world use.