On Wednesday, May 2, 2018 at 2:12:24 PM UTC-4, Dirk_PW wrote:
Had this pilot been equipped with ADS-B "out" and no SPOT or other alternate means of satellite communication/alerting methodologies, what would have been the sequence of events for finding him? ...

Is ADS-B 'out' a reasonable alternative to SPOT or is it just riddled with too many limitations ...

I don't have the complete answer to your question but https://flightaware.com/adsb/ uses a network of receivers to track ADS-out aircraft. Their coverage exceeds ATC coverage. You can track individual flights.

I think that it is better to have more than one way to be found.

BTW, does anyone know if FlightAware tracks SIL=1 TABS?