I used to own the Makro Jeohunter 3D Dual System and have experience with the Nokta GoldenKing Plus. The large sized coil was always inconvenient because it took two people walking in unison to wield it properly. But there was a significant increase in depth penetration between the medium and large sized coils so if you wanted to look deeper you had to use it. I spoke with a dealer about the Nokta Invenio yesterday and got to see it in person. Nice looking detector with craftsmanship that seems top of the line. According to him, the large sized coil on the Invenio can now be wielded by one person due to its decrease in size/weight, yet the depth penetration has increased by 1-2 meters more than the large sized coils on the Jeohunter and GoldenKing. If this is true it is a very significant upgrade. Can someone from Nokta confirm these claims? What is maximum depth penetration with the large sized coil on the Invenio? It would be helpful to have a depth chart describing what size objects can be detected at what depths with each coil. Thanks