Single versus split power supplies for op amps
In my application input can be AC but the output needs to be a DC
  referenced level (being fed into an ADC, 0-2V5)


If your application is AC then you can couple the signal via a capacitor to a 1.25V reference voltage provided by resistors - this sets the average voltage at 1.25 volts i.e. half the ADC range. This strikes me as the easiest way to deal with this application.

If your AC signal is differential then you might consider using an instrumentation amplifer but this may likely have to operate from split supplies.