Bob,
Two of the most likely-to-compare models on the market are the Minelab X-Terra 70 and White's MXT, mainly because there two multi-purpose models feature a fast auto-tracking circuitry.
I had four (4) of the MXT's and one of the things I generally did was balance the unit and then 'Lock' it at that GB setting. Very seldom do did I use the tracking function with the MXT, M6, XLT or XL Pro.
What especially impressed me about the X-Terra 70 was the added feature of Auto GB and Manual GB. Personally,
I prefer to have control over most functions of any detector, and this especially applies to dealing with ground environment challenges.
One thing that I have experienced with both the fast-tracking M6 and MXT in the highly mineralized ground where I usually hunt is the potential to 'lose' a smaller, deeper or "iffy" target. By "lose" I mean either I didn't get a response on the 2nd or 3rd, sweep, or in a few instances I didn't hear the target at all on the initial sweep. This is when evaluating the detector over several target hits located with another make/model or with the tracking locked on the M6/MXT.
I also worked them with and with-out tracking when evaluating potentially good targets (non-ferrous) in a mix of iron trash.
Along comes the X-Terra 70 with more operator-control of the Ground Balance function. I was pleased! I took it to the same locations where I had known located targets nd compare the X-Terra 70 with the MXT using a fixed GB and the Tracking functions of both.
When finished with my comparisons I came to the conclusion that both of them might miss some deeper, questionable targets when using the auto-tracking feature, but the X-Terra 70 did do a little better. I was able to get a first or second sweep hit off of a smaller, deeper target that the MXT either didn't respond to, or only responded to on the first pass.
To compare how fast their tracking circuitry worked I let my friend try it for a demonstration. I had him stand in a wood-chip playground where the chip-fill is several inches deep and the X-Terra 70 would GB with a GBRN (Ground Balance Reference Number) of 43-44. Then I lined out a straight path for him to walk, sweeping the coil at HIS typical sweep speed. This 15-18 foot walk took him towards the grassy park corned, across some lawn (GBRN or 14) and onto some bare dirt (GBRN or 12). He was used to using his DFX and moved along rather briskly. Not the speed that I would hunt, and the X-Terra 70 was very quick to adjust the TGB. Faster than an MXT I compared at this same location and same 'test' walk site.
I found that interesting because while the X-T 70, for me in my tests, seemed to track the ground a little faster, it also retained some good smaller/deeper target performance compared to the MXT.
Naturally, different coils would also possibly change the performance., but in the end I determined that I really like the X-Terra 70's Tracking function. I used it more than I did that of the MXT or M^. However, I am still used to setting the GB myself after all these years and that's what I prefer to do.
Maybe you can locate an area to grid off and hunt it with the X-T 70 manually balanced and use golf tees to mark targets you would go after that might be questionable. Then, re-hunt the site using the Tracking function and see if it makes any difference for you, good or bad. Then YOU will know what it offers YOU!
I know I like it in lower mineralized sites that are lower in trash, but there aren't many of them around here.
Monte
PS: My friends, Cris & Tom are in the NE again and are eager for any invites to take them to hunt older-coin sites. They use the Minelab Explorers and would love to see how the X-Terra 70's do in the same area.
Chris' cell phone number is (503)309-6940 and they will be traveling in MA, NH, PA and other NE locations. The brought rain gear and cold weather gear, so if you're inclined, give them a call and see if you can meet up with them.
