Metal Dictator,
There are SO many types of tabs out there; for me, whether it was with my Explorer, my CTX, or the new Equinox, the different types really span a wide range from just above nickel, to just below zinc cent. With that said, though, there are VERY FEW that hit RIGHT AT the nickel number, on my old Explorers or my CTX...though one VERY prevalent variety hits JUST above nickel. So far, a couple of short hunts with the Equinox reveal the same thing. VERY few of them dug right at the nickel "13" ID. I think I dug one or two that bounced between 13 and 14, but only ONE did I dig as a solid 13, and it was bent on one end, which is probably why. Otherwise, 14, and above, is where they hit. Lots of them at 14. FWIW, a moderate depth Jefferson I dug was a solid 13 in the dirt; the Buffalo nickel that was a tad deeper, 6-7", was a 13, with an occasional bounce down to 12. SO -- I think square/rectangular tabs can be generally said to hit just above the nickel "13" number. Likewise, beaver tails ring at 11 or 12, just below the nickel "13."
mrmetaldetector --
ID numbers are the same on the 600 and 800. And, while I haven't tested it personally (I've hunted exclusively in multi-frequency so far), others doing testing have noted that ID values are stable across all frequencies, including multi-freq, and across all modes.
Steve