I think it is better to focus on a single fixed exchange rate cryptocurrency with a large warchest. There are several reasons:
1) Currency is most useful if it is accepted by a large community. Thus, it makes sense to focus on one single fixed exchange rate cryptocurrency to encourage broad usage.
2) The credibility of the exchange rate depends on the size of the warchest. You really want an exceptionally large warchest to prevent a speculative attack on the fixed exchange rate. If you establish several currencies then the warchest of each currency will be small. The exchange rates of each currency will not be credible. Better to have a single credible currency than a multitude of untrustworthy currencies.
3) I do not think it is a good idea to keep the warchest in a form that could be easily frozen by a corporate controller or a government regulator. Thus bitcoin is the best option as a secondary asset.
4) Competition is often harmful in finance. The problem is that competition encourages risk taking and fraud. Monopolists have a strong interest in preserving the status quo. The trustees could earn some income from fees for example. This is a good thing because it makes it unlikely that the trustees will rip-off their users for a one-off gain (looting the warchest or gambling with the warchest).