Haha. I don't dispute that there are machines today, that are far superior , at low conductors (alloyed gold jewelry) than the selections of the mid to late 1970s. Back then the work-horses were the VLF/TR machines (that could not find dainty chains or earring studs, unless you had it in all-metal mode). And the 6000D, for example. Which was great on silver, but not so keen on nickels and low conductors as much. Even all through the 1980s, the powerhouse motion discriminators coming out were great for silver, but not so keen on low conductors.
Versus today, yes, you have machines that will do fine on deep silver, yet .... can be tweeked to "ring the bells of Notre dame" on teensy low conductor stuff, all at the same time. Thus yes, theoretically, they should be "better on [alloyed] gold", right ?
Yet there's never been a time, in the 1970s to the present, where md'rs couldn't have gone out, even with the old machines, and "filled their aprons" full of low conductors. eh ?
The only benefit of the new breeds of machines (like the Nox), in-so-far as ability on low conductors, would be if someone wants to go angle for micro-jewelry. If so, then heaven help that poor soul if he ends up in a junky park. And sure, the beach is less punishing (assuming you're on the wet inter-tidal when mother nature has washed out all the light aluminum). But eventually, you have to ask yourself : After you've gathered a dozen tinsel thin chains and some earring studs, you come to the realization that a SINGLE SMALL RING outweighs the combined weight of all the micro-jewelry.
Perhaps the new breeds provide a cross-over to nugget hunting. But as far as gold jewelry, no, I don't see any advantages, given the type places we md'rs hunt. There was never a lack of low conductors to choose from, in the first place. Wake me up when they've invented a machine that can tell aluminum apart from gold.