Problem is, whenever I ask those posters how exactly that is achieved, they have no answer. To me, unless it can be explained in a technological manner, then the anecdotal evidence doesn't mean much.
Unless you hook up an oscilloscope, I'm not sure how anyone can explain things in a technological manner, but I'll try. I don't even use a 3030, but to me, its pretty much an E-Trac with more bells and whistles (at least the underlying FBS technology is).
I believe FBS sends out lower frequencies than the D2, even in the HC program, but you need a scope or a reliable source online to verify this. I do not believe Minelab publishes this (if they do, I have not seen it). Lower frequencies are good for deep silver.
Operationally, the settings "response long" and "sizing pinpointing", as well as a very slow sweep speed are the secret sauce on the E-Trac. Maybe the 3030 has these settings, I dunno. I do know I have not found how to do response long on either the Nox or the D2.
This stuff will tell you if it is a coin-sized object. Next, the tones and TID of the FBS machine (at least the E-Trac) will distinguish between silver and clad about 75-80% of the time. I have not found a way to do this on the Nox or the D2, but maybe there is a way, I dunno. Digging clad will kill you, at least in park and school settings. I may miss some silvers, but I'll be swinging and covering more ground while the competition is digging clad in rock hard dirt. Moreover, the D2 in the HC program makes pull tabs sound like desirable targets; perhaps my machine is a lemon and others have not had this experience, but it really slows me down when a pull tab rings higher than a wheatie, and sounds so good.
Yes, silvers in iron are anecdotal, but I've dug enough of them that I can hold in my hand; iron stained and so forth, to know that the FBS machine can find these things, if you swing slow. I think there is really very little choice but to be anecdotal, as properly designed experiment has so many variables, that I doubt anyone has the patience to design one. (I know I don't, even tho I have a pretty good idea how to design controlled experiments, being an economist).
Which brings us to the larger point. What choice is there to be other than anecdotal? Consider the variables that have to be controlled for among 2 different detectorists: hours swinging, mineralization of their dirt, historical population density, skill at research and permission for getting good sites, skill of their competition, and so forth.
So, when I hear I've found X silvers with machine Y, what does it mean? As much as I love success stories, not much when deciding on a machine. I've found 35 silvers this year with the E-Trac, which I think is pretty good, considering my hours in the field this year (a better way to look at it is silvers per hour, but that only eliminates one variable of many). But people are selling their E-Tracs and 3030s in droves, so what does that mean?
I don't think anyone is ever going to design a bona fide head to head experiment between 2 machines that controls for all variables. It takes such a rigor that most don't have the patience or training for. I've never seen a properly done head to head experiment myself, tho I did do one myself between the V3 and the E-Trac back in the day. It was way too much work to do again. More efficient to buy all the machines in question, and sell the ones that don't work for you. About $300 of risk with the D2, way cheaper on an hourly basis than the time to design and perform a proper head to head experiment.
So, if you believe that, we are left with anecdotes, and what we must do is aggregate them. Crowdsourcing if you will. While economists tend to be process rather than outcome people, we almost think in terms of crowdsourcing. Crowdsourcing is what sets prices in a free market, for example.
So, you suck all the anecdotes into your brain, consider the credibility of the source, and your brain churns and churns, and eventually comes to some sort of average opinion of the crowd as to which machine is better for what you wish to accomplish with it. This is what happened with the E-Trac vs the V3. No oscilloscopes, no technological explanations, the crowd determined via a mountain of anecdotes that the E-Trac was the better machine than the V3 for finding deep silver, and the crowd seems to have been right.
So, I see the preference of a technological explanation over anecdotes, but I just don't think we are going to get a properly designed experiment (air testing and test gardens are worthless, IMHO). So, all we have is crowdsourcing/aggregations of anecdotes. That is one of the reasons I, and others, feel the need to debunk certain charlatan(s) who pump certain machine(s), and dis other machine(s), but never seem to find much except in their test garden. They have an inappropriately outsized voice in the crowdsourcing domain.
JMHO
