Merely enhancing the role of the SDR would do little either to increase the flexibility of the system or change the incentives of surplus countries. By providing a ready swap of existing reserve currencies into a broader basket, SDR reserves could also further displace adjustment onto other freely trading currencies, thus exacerbating the imbalances in the current system.
Indeed, by providing instant diversification, SDR reserves could entrench some of the existing strategies of surplus countries. This would change if the proposal were taken to its logical extreme: the SDR as the single global currency.