LOL! I don't think anything pertaining to metal detecting has been "perfected". If Minelab has perfected the metal detector, how can they make it better in the future? Which one perfected it, Sovereigns, Explorers, Etrac, CTX, Equinox or Vanquish?
Do a search on silent EMI. It affects different detectors differently. One may attenuate a certain wavelength better than another but worse than the other with a different wavelength. Mr. Dankowski has had silent EMI cause a difference of 2 inches in depth from one day to the next with the same detector, an Equinox. He carries a dime to check depth before choosing which detector to use and it changes even in the same area. Just because one detector is deeper in one instance does not mean it will be deeper all the time.