One another site, I read that Navionics started using a different provider for their "base maps" in either 2008 or 2009. The new "base map" doesn't have as many details as the old.
I also read that after a HD survey has been implemented that many of the details such as channel, roadbed markings, etc are not on the HD map
That is why I shopped around for a 2007 premium card.
I haven't been able to verify if these rumors are accurate, but my 2007 premium has very good details for lakes that I fish that also are not HD.
It would be nice if Navionics and Lakemaster had half as good of support on these forum as Humminbird has.