The question is what do detectorists do? are they out there to dig up 'neat' shiny things, or are they trying to throw light on the past. (Do they record meticulously what they find, along with the contextual information, do they publish their findings in journals available to others in the field? I would say that Im sure that while there may be some good in the service the 'detectorists' may provide in drawing attention to new hitherto unknown sites, they may, in their haste to dig up neat, collectible objects destroy other information about the culture where those objects came from. Information which is then irretrievably lost.