As it turns out, my friend is going to bring that gold necklace in question, to my house next month . For a get-together we're having with some md'ing buddies.
And one of the friends has the Sov. that he'll bring. We'll test the said-necklace with the Sov. and see what happens. I have always been of the opinion that the Excal, Sov. and explorer achieve the same end-results, when it comes to ability on smaller-gold. But we'll see if the Sov. is somehow better on this particular item.
One difference I've seen though, for the Sov, is that it has the unique ability to get insane depth (with seemingly no loss of sensitivity to small stuff) when going to the Wot coil. Versus the Excal and Explorer, both of which I tried the WOT on : All it did was get more coverage/swath. But not more depth on coin-sized targets.
Ie.: The explorer and Excal seem to hit a "point of diminishing returns" at about the 11" coil size. But Sov. does indeed get more depth, on coin sized targets, when going to the bigger coils.
If I didn't detest the annoying audio of the Excal and Sov, I'd be using them