The all-digital signal in DC is an interesting experiment and I would love to hear how it sounds on an HD radio.
While WWFD is licensed in the Washington metro, it is a very suburban signal. Its 10 mV/m does not leave far-off Fredrick Country, covering about 120,000 persons in a market of 5.8 million. Its 5 mV/m barely nudges Montgomery County.
But, to make the point, all-digital AM sounds every bit as good as analog FM.