Maybe this sync-with-my-native-calendar stuff is a blind alley. Maybe the best way forward is to put Google Calendar everywhere and just finish figuring out how to sync everything else to it. (That is, if you don't mind Google knowing where you are going to be from hour to hour.)
However, listen to Dave Taylor, writing back in January: "Google Calendar, however, is completely incompatible with the [Blackberry] Pearl and any other mobile device."
Gmail has worked fine on my Pocket PC for a while now. I wonder when we'll see Google Calendar on mobile devices?