The most resilient currency system is one that has at least two levels, international and regional.
Using an international currency only, produces a "tightly-coupled" economy that is highly vulnerable to the propagation of shocks throughout the system. On the other hand, a system comprised only of local or regional currencies creates de-facto trade barriers between regions. A dual system enables trade but in difficult times enables those regions that are still economically functional to continue to operate and to a certain extent assist the troubled regions in getting back on their feet.
This, like most of what I have to say, is an engineering-based model... It produces obvious predictions: that in a coming crisis, areas with local or regional currencies will be more resilient than areas that depend entirely on global currencies (dollar, euro), thus the development of local curency systems is a key ingredient in local and regional preparedness.


