It might be helpful to know a little more about specifically what you're trying to find out. Since the concern is low flows, are you trying to model sediment transport? days of inundation for the wetland? other?

Also, it would be useful to compare the needed accuracy of the hydraulics of the model with the uncertainty/accuracy of the other inputs. For example, its quite likely that the unknowns on the hydrology are at an order of magnitude more severe than any unknowns you might have on specific stages due to flow splits in the braiding, inaccuracy in channel lengths, etc, etc.