The minelabs you listed, and the Fisher's you listed, would do about the same on mineralized wet salt. But it also depends on what you mean by "mineralized" (ie.: HOW mineralized). I don't know about your state, but where I'm at in CA, we can tell the amount of mineralization on a beach by two ways: The color: if it is a white-sand beach, then it is non-mineralized. If it is light brown-ish cinnimon colored, it is moderately mineralized. If it is a gun-powder greyish tint colored, then it's getting pretty nasty. And if it's metallic black in color, it's absolutely thrashed with mineralization. The colors can vary on the same beach, depending on gully washes, dry sand verses wet sand, etc... Another way you can tell the mineral content, is to take a strong magnet, and see if dusty particles stick to the magnet. The more that does, the worse the minerals. I've seen minerals bad, that if you took a baggie of the sand, a magnet would litterally stick to the outside of the bag!
If you've got any truly nasty badly mineralized beach sand (like would be found in gully washes where they exit on to the beach after rains), then neither the Minelabs you mentioned, or the Fishers you mention, would work. In the worst mineralized beaches, you'd need a pulse machine. But the downside there, is you'll have no way to reject nails and iron (barring guessing tones and such).
Assuming moderately mineralized beaches, it's a matter of preference for the units you list. The Fisher's would certainly be easier to operate and learn, as they tend to be turn-&-go, beep-or-no-beep type machines. But other people do not like the silent search, prefer the more expanded tone ID, and expanded control options of the Explorer. I would go for the Explorer. At first, the warbly sounds will drive you nuts. But as you get used to it, it will be music to you