This is a feature of variable rates which allows markets to distort things inside economies. The problem with the ERM was it was neither fish nor fowl, a banding system which could be changed or ignored.

The Euro resolves a lot of the ERM system issues but you do have to go in at the right time and then manage the problems that will occur while economies get in sync.

The problem I really see with it is it needs far more convergence on taxation and other policy than we currently have in Europe and that's possibly going to sink the whole thing.