Sure, there is always going to be exceptions to the rule. But, under the same ground conditions, then in general, the older the coin, the deeper it will be.
Also, I recall something about the E-Trac having a slow recovery rate due to FBS and/or an older, slower processer. If that's true, then that would be a significant detriment in trashy sites.
Yes they do get deeper the older, generally. I'm just saying that here in southwest Kansas dirt, hard packed, unless I'm hunting in the flood plain, then most coins I've found over the years have been 5"-6" or less. In a front yard, for example, I found a 1863 3 cent piece at only 2" deep.
Yes the FBS does require a slower swing speed than the newer machines I have learned the key is the threshold. Like my yard is littered with iron my E-Trac is a solid null unless I move the coil at a snail's pace. As long as I can hear the threshold, I know my recovery is fine.
Masking isn't as much of an issue if you use to know what to listen & watch for. While there may be a piece of iron that keeps the E-Trac from giving a good conductive target tone, because it has 1500 TDI segments, you can hear & see the difference in just a piece of iron, or a piece of iron with a conductor by it. As I said, so far there has been little found I have missed, I am just at my E-Trac maximum depth without just digging anything that makes a sound. That is futile.
As I stated before, I've had people take me up on our park before. I had a guy from Kansas City or Missouri come down with several of his hot detectors. Of course, this was years ago, but I had him check 6 targets my E-Trac called good, and each one he called as junk. Every one of them was an old coin. Two were silver. When he left, with clad and one buffalo, his exact words were "I need to reevaluate my thinking on the E-Trac".
Here's the deal. If this new "unmasking" technology is more than hype, then someone will have a killer time. IF these new detectors can reliably, by reliably I mean accurately, get to 8" and deeper, then someone will have a killer time. IF not, then someone will learn a valuable lesson LOL.