fine, directv has better signal quality than comcast digital in san francisco. i can't speak about other locations & services, but here in SF, satellite has better quality.
and you may be right about the provider specific broadcast, but as far as I know, almost all cable campanies broadcast the lower channels (locals + channels 30-80, something like that) in analogue. the only thing that is usually digital in digital cable are the channels that come with the digital package, i.e. the higher channel numbers.