The only problem I see with using the Vanquish (540 and 440 in particular, not sure about 340) with 5"x8" coil for small gold is that it has no adjustable ground balance. Multi-IQ (the multifrequency technology on Equinox 800, 600 and all three Vanquish models) derives its ground cancelling from analyzing responses at different frequencies during operation. That works in some ground but as the mineralization increases, its effectiveness drops. For the Equinox models, besides this option, the user can choose manual, auto (what Fisher calls "Ground Grab"), and tracking ground balance, but not on the Vanquish.

I don't know if the ground everywhere in NW Nevada is too tough for the Vanquish as that does vary, but being able to ground balance in areas where native gold is found is the way to go. I think all dedicated gold detectors have some kind of ground balancing to handle at least moderately high mineralization.