DGPS is a quantum leap in accuracy over GPS.
Unfortunately, to gain maximum accuracy from DGPS it requires either a portable base station set up for serveral hours or a permanent base station(s) mounted high enough for wide area use.
Many public entities are installing DGPS base stations for use by the public. We are installing one on the roof of City Hall here.
When the permanent base station is installed we will be able to use the "Holy Grail" of sateliite navigation - Real Time Kinematic Differential Global Positioning System. "Real Time Kinematic" means that the rover is continuously tracking and can take and store THREE dimensional readings every second if you want. I have seen a topographic map survey done by a guy on a four-wheeler just riding back and forth. He could do a weeks work for a survey crew with state of the art equpment in one hour.
The future goals of RTKDGPS include having base stations at every airport, harbor and large city.