Not an expert either, but in my area (Southern Arizona) the gold is pretty small so most gold hunters use the Gold Bug II or Lobo SuperTraq. Gold Bug is higher frequency and probably a little more sensitive but also has more problems with black iron sand and hot rocks.
In my opinion the LoboST is a better all-around machine because it does have a passable discrimination circuit and the ground tracking is phenomenal. It goes super deep and you must get accustomed to using a nugget scoop because in All Metal mode it will sound off on every miniscule bit of rotten screenwire, tack or #8 shotgun shot. In Discrimination Mode and the Disc set at about 2 or 3 it will weed out most iron but find lots of really deep non-ferrous relics, garbahge and assorted junque. It also has a lifetime warranty and I hear Tesoro is extremely good at honoring it.
Marc