A large society has many many many problems that I think are avoidable via smaller structure, or at least through localization. I think a certain degree of unity between tribes would be necessary in extreme times, but in general, they would be kept seperate.
Being American, I can't help but think of U.S. History here. Our orriginal constituation, The Articles of Confederation, set up a system similar to this (Although on a larger scale than desirable). Power was focused on the state level, allowing each region to develop independently and uniquely; the Federal government was largely inobtrusive and essentially was to unite the various states in times of war when cooperation would be unquestionably necessary.
If I recall correctly, the primary reason for ditching the Articles was because they hindered economics.
I would expect that a "metal society" would not sell it's soul in order to profit more economically. For one thing, standardization of currency does not need to mean strong central government, for another, I think we all agree that a strong trade economy is NOT a goal of our hypothetical society.