I had an old DGPS that finaly bit the dust. I think it was a GP32, but not sure. I'm looking at a GP33 or GP39 for a replacement which doesn't appear to have DGPS. What am I missig out on by not having DGPS? The old unit was pretty solid when i was staying on the fishing hole. I see the higher end units still have DGPS. I tried using my backup gps(garmin) this weekend and the heading would change as the boat rocked and pitched. A real pain. I just don't want to get back into that situation.