Your last paragraph is very similar to what I've read is going on in the European Union with the Euro. (I don't remember what book I read it in)

Basically their argument was that it works in America because the federal government is strong enough to redistribute wealth to places that can't keep up. In Europe the federal government is weak, so the southern countries have an economy they can't keep up with.

I don't remember the specifics, but that was the gist of it.