[Paleo Conservative]

AOA is a powerful tool, but in my experience it is less reliable than normal pitot static instruments. Even in carrier based planes where AOA is the primary landing speed instrument, we always checked it against airspeed before commencing the approach.

By incorporating it in the MCAS system, Boeing is making AOA a primary flight instrument. I would think you could add a comparator between the two guages, with an associated light, and corresponding procedure.

Probably more than just compare the two gauges. I don't think I'd want to be flying ETOPS 180 in a 737 that can't figure out which AoA is faulty. Two gauges just means you can tell that one of them isn't working correctly. How are the avionics going to figure out which one to use?

[USNBandit]

That is what the procedure is for. The comparator is to warn the pilots of a problem with an indicator most people don’t scan, except maybe on final.