Your precision measuring circuit examples all recommend using a differential A/D measurement to subtract the (potentially drifting) internal reference voltage from the signal voltage.
Would a dedicated external precision reference voltage source, fed to the REFIN pin, and not using the internal reference, be potentially just as good and allow single-ended voltage measurement with comparable accuracy ? Or is it essential/required based on the architecture, current draw etc. to always measure the field and field changes as a function of (Vout - Vref), no matter if external or internal reference voltage is used ?