Seems like HD Radio is in the same boat as HDTV, neither have many channels to choose from. It is very common for someone to purchase an expensive HDTV only to find the picture horrible when they get it home. The reason, you can usually count the number of HD channels with two hands.
The same with HD radio. Not many HD FM stations are available, maybe a dozen or more in larger metropolitan areas. If the religious broadcasters are catching on, which I suppose they already have, they will have the potential for a bigger audience who will give their programming a chance if there is nothing else on.
But that is today. If consumers keep buying into HD it will encourage (and possibly financially support) more HD content to be created. The more content created, the more channels needed to broadcast it.