I can pick up a Rino 530 for about $400 or GPSMAP-60CS for $346. I see the Rino does not have an external Ant. hookup and the batteries don't last as long and the display is smaller too. I want to be able to use it while in my car, would I need an Ext. Ant. hookup? I don't think I will run into anyone using a Rino so the position-reporting capability is of little use.