It really is almost impossible to keep a GPS device off the boat, iPads, phones, all the small handhelds, many cameras and even the diver lifeline radios are capable of recording a position. If you have a real secret spot you can expect that it won't stay that way for long anymore.
Early on it bothered me a lot back when many of the sites I hit were exclusive and hard won. But then there were not many handheld units out there and I could just guard my loran when on the final hunt. Now that most all the sites we hit are fairly well known I just don't care. However, they won't be going to the few sites I have left that are not really public. If I told a group not to GPS and found out they did it would be their last ride with me.
Years ago I had boats following me over half the ocean hoping I would lead them to the 701. We had a game of cat and mouse many times over that and someone even tried to use my nav unit to get numbers. Today they could just follow along on the AIS but I have an off switch for that if needed...