The bonus of investing in ECU (and why I chose silver miners above pure play gold in the first place), is that silver has increasing numbers of industrial uses, as well as currency.
Whatever happens as regards the introduction of SDR, is it liquid, can everyone access and invest easily? many countries will continue to trade the USD over the next 10-20 years because it's a currency which they alreayd have and can be easily exchanged for local goods and services.
How will SDR protect against the coming inflation (all global currencies are being debased - any move away from the dollar is likely to increase the spectre of inflation in the US imho). How will the value of SDR increase to make it an attractive investment vehicle, and therefore what is in the impact on local currencies?
Arabs and Indians won't find SDRs that attractive an investment vehicle, there's no match with the Koran and you can't pin an SDR around a Brides neck on her special day.
JMHO
AP