I hunt iron relics, while not digging nails, with my Tejon. Most detectors have iron larger than a nail, lower in the iron range. Your right though, the majority of hunters do not want to dig any iron.
I don't nugget hunt but from hearing on the forum, the Equinox 900 or Nokta Legend will perform better for nugget hunting. The 6" and elliptical coils are better than the 11" coil on nuggets.
There should be an update for the 600 & 800 also.
I saw a post claiming the Manticore is more sensitive to gold than the Equinox. There is no 6" coil for the Manticore though.
I haven't heard if the 700 & 900 are updated too. I hope they gets updated with Stability like the Manticore. Also increased sensitivity to gold. I would be tempted to get the Equinox 900 if it gets the upgrade.
Enjoyed reading your story. I started with a Compass 77b Professional. TR detector. 100 khz. It was strange, no discriminate but would not hit a nail. Easy to go thru and dig everything.