Joe, I've had a couple MXT's over the past few years. And, they are good detectors. Although many of the features of the MXT and X-70 are similar, here are some of the reasons why I prefer the X-70. The MXT offers single tone audio in the C/J mode and dual tone audio in Relic. The X-70 offers your choice of one tone, two tone, three tone, four tone or 28 tone audio in all modes. The MXT offers variable discrimination control. The X-70 offers notch discrimination and provides 28 notch segments in two-segment increments. The X-70 has Auto Noise cancel for those areas with RFI. The MXT does not. The MXT has knobs, which I use to consider a "plus". But I've found the touch pads of the X-70 are far easier to access while hunting.
I think the turning point for me was an old farmstead that I hunted several times this past spring. All the buildings had been gone for the past 75 years. And the ground has been plowed, planted, disc and cultivated many - many times. The buildings that were once there were apparently burned and not torn down and removed. The ground is littered with iron scraps, old cut nails, pieces of farm implements and melted metal. Although both detectors get fooled once in awhile with deep pieces of iron, the MXT was much worse, by far. In one afternoon, I nearly filled a 5 gallon bucket with trash from that site, using the MXT. Regardless of how high I set the discrimination, it just wouldn't ignore that old deep iron. I tried my shooter coil, the 5.3 Eclipse, the 6X10 DD, the stock 950 and even the Super 12. Needless to say the smaller coils were better able to separate the targets. But even with them, I just couldn't eliminate the iron. When I hunted this site, I was field testing the small coils for the X-Terra. Both 6-inch coils, as well as the stock 9-inch at 3 kHz did a much better job of correctly identifying the iron. I typically hunt in the all metal mode, four tones and high sensitivity. I ignore the low tones if they are the only signal at any one particular spot. If I get a high tone and a low tone adjacent, I switch to Prospecting mode to separate the targets and determine the size of each. The only "problem" I had was getting quite a few high tones on deep iron. Especially round objects and rusty chunks of implements. But, by simply checking the TID, I would see that they usually bounced in at a +48 on the TID. And by sizing them, I could determine that most of them were bigger than a coin. Oh, I did dig some trash. Mostly old iron harness rings and a few pull tabs from where someone drank some cold ones! But not nearly as much as with the MXT.
As I said, both are good machines. But for the type of hunting I do, and the places I hunt, the X-70 has done a much better job. Lighter weight, better balanced and half the batteries! JMHO Randy