Never tried one, but my opinion is this- There is no magic wire that makes them aftermarket coils better. They can shape the windings for better separation etc. but that is about it. The coil is made and tuned to the freq. of the detector. The coils characteristics are determined by coil shape, conductance, capacitance, and resistance. The correct number of turns shape, and size determine the tuning for each specific frequency. It's no magic and my guess is the manufacturer knows how to make the best coil for their detector. Claims of amazing extra depth are bull. As far as shaping the EMF field of coil, the DD is not a knife edge as shown in pictures and the concentric is not perfectly conical. Those pictures are just to give a layman idea. The truth is the shape of the field is a lot larger and uglier than the pictures everyone shows of a conical and DD.