I hate to beat ya'lls dead horse here but I'm gonna take a whack at it anyway. Hahah.
The eTrac is a fine detector I'm sure. I had its predecessor, the Explorer II. I've only had the eTrac in my hands and played with it but I have talked to several folks that know it well, and basically they've told me that it's an Explorer II with a new coil and a tad bit faster processor to speed up recovery rate, but it's still not great when you put it in iron trash. If you use discrimination on them, it slows down the recovery rate and thus it will null on about everything you have it set to knock out, and therefore masks a lot of targets when in a trashy area.
Thus enter the ultra fast processors of the F-Series detectors and the carrying on into the G2 and Gold Bug platform. These machines by default, are going to enable you to work around iron trash better because they aren't nulling out on the iron, and lightning fast recovery rates help them see targets in close proximity to trash targets.
Each detector is a tool. You wont find just one tool in a mechanics tool box. He might use one more than the others, but each tool has its own application. Detectors are the same way. For extreme raw depth, there is nothing on the planet that can compare to the Minelab GPX series. But you'd be asking for trouble if you took one of those into a trashy park or old homesite. That was my problem...I already have the detector for maximum depth capabilities. I was looking into one for fast recovery for trashy sites, light weight, and overall fun to use. Of the models I looked at and took a demo spin, the Gold Bug was my favorite and thus why I ordered one. It filled the gap in my tool box.
For kicks and giggles though, when I had the Explorer II I also had just purchased a Ace 250. I was hunting an old football field near the concession stand area, where I had dug some wheat cents and silver dimes in the past. I had gone over the area many times with the Explorer and other machines, and had came back with the Explorer and the 8" SunRay coil because it is quite trashy there. I hunted for a little bit and picked up a couple wheaties and decided to give the 250 a spin. In less than an hour I had dug 2 silver dimes and a few more wheat cents with that little Ace 250. I was checking the targets with the Explorer because I wasn't that sure of the Ace 250 yet, and on both those silver dimes, I could only get a signal one way, and the 250 was singing out strong and locking on ID. So if I were to just post on the internet and say my results from that one hunt...the $200 250 outdid the $1000 Explorer II...well in that instance it did BECAUSE OF THE TRASH and the faster recovery of the 250 but in others, the Explorer II would beat it. The 250 was just better in trashy sites and that particular location was just that.
As pointed out too....Gold Bug = gold prospecting machine. People are just utilizing it for coins/relics/jewelry as well. The same is happening with the Whites TDI and Minelab GPX = gold prospecting machines that folks are using to coin/relic hunt with and being very successful at it. Raw depth, they can't be beat! But in trash....ouch.