I have the older 7" coil model and it goes pretty deep in my decent soil here in Kansas.
The sense is also turned up to max internally, too.
My 7" was very stable in both soils I have used it, Alabama and now here in better soil in Kansas.
I was just sent a new 8" model to try out from a very gracious owner that is working so much he has no time to use it so he is lending it to me and I am in the process of putting it though its paces.
So far I have been on 2 short hunts with it and it seems pretty impressive for a stock unit right out of the factory.
Me, I would definitely be getting inside this thing and mess with the sense if I owned it.
I am in the process of writing a much more in depth review of this unit on another forum, but I will give you the Cliff notes on what I have found so far.
I am most curious about how razor sharp the disc is compared to my older model, (and my Vaquero), and also its target separation abilities.
I have found the older 7" model is fantastic on the first, and even though I have never tried the 5.75 coil model I have to believe my 7" is just as good as that one as far as target separation do to the fact I have used it for many hours at some very trash infested sites.
My hope is that this 8" coil model is just as good or at least close.
Depth is something that needs to be tested also, but I will have to hit some other sites besides my mostly newer parks for that.
So far I have discovered that unlike the older Compadre and my Vaq, zinc pennies do not seem to disc out at exactly the 3:00 position like they do every time on my other Tesoros, but the knob is slightly forward of that position.
To correct this one might only need to simply to loosen and reset that disc knob a bit that some owners do on many Tesoros they use.
I have also found that on those zinc pennies, and also several lead weights I dug since my first hunt was near a lake, unlike my older Compadre, this new one is not quite as razor sharp on the disc as I turn past the fade out point and then back down to listen how the target comes in...something I do on every target because I think it is way more accurate then dialing up the disc knob the way Tesoro says to do it.
I do get a little fuzzyness, some crackling and clicks from time to time on my Tesoros on some zincolns too, but not on every one like this unit seems to do.
This is not a deal breaker, just slightly different than what I am used to.
Nickels are strange on all my Tesoros and this one is no different.
I have dug 3 so far and one disced out where it should right at the 5 cent mark, 2 others were gone way before that mark one almost to foil, but I have seen this happen a lot on my other units, also.
The great thing is foil, can slaw and tabs usually break up at the end point way more than good targets so I can get a pretty good idea on what is trash and what is not, and larger can pieces are usually louder and have a tinny annoying sound to the signal that I experience on my others too.
Depth seems pretty good on the deepest coin sized target I have dug so far, a UMC New Club star shell that was about 6" deep.
Keep in mind I don't want to scratch the coil on a detector that is not mine so I am swinging at least 1" over the ground but actually more like 2".
If so, this shell was a solid, repeating signal from all directions that sounded deeper, not so loud and further away just like it would have on my other units, and it did this at about 8" in depth.
Again, I believe turning up the sense can probably get me further past this 8" mark, especially in moist ground, but I will try to find other sites and see how deep I can find coin size objects with this stock unit in the near future because I suspect it can do that with factory settings.
I don't believe so much in air tests or on targets that are recently buried, I prefer to do my depth testing on real world targets in the matrix of undisturbed soil so I will try to do that on some hunts in the near future.