When I was using the Tejón just before and shortly after it was released I took them (I went thru three -3- specimens) to a wide variety of sites in four states, as well as to many locations in the Portland, Oregon, metro area that had electrical power challenges.
In particular I worked four locations that have a very high ground phase reading as measured with a White's MXT. The sites were all in the 81 to 87 range, but different in appearance and 'texture.' At the sites with a high reading but a more loose and porous ground material that you can easily toe-scuff to 6" or more, the Tejón got fairly decent depth. It compared favorably with many makes and models, <EM>usually</EM> better by an inch or so over other Tesoro models. However, in the "bad ground" that was much more compacted and had a darker appearance, the Tejón didn't work nearly as well as many models, to include Tesoro's own Eldorado.
I worked near some powerline challenged sites as well. One was a park and play field where there were power lines running overhead along the south and east sides of the park. Here, a Cortés and DeLeón were relatively quiet with the stock coil if you stayed at least 40'-50' away, but with a 10x12 or CleanSweep coil it was very noisy unless you were a good 150' away. Part of the problem was associated with a bad preset GB being too negative.
I used the same coils on a Bandido II µMAX and Eldorado. Both were quieter than the other two Tesoro's with the Bandido II µMAX being the winner. This was with all models set to reject the same target.
I then took the Tejón's there using the stock 8x9 coil. I could not work any closer than 50+' or so w/o noise.
I then went to a series of small playgropund sites that are located along a "green space" that runs along a hilly rural area where there are tall, high-power transmission lines. Even though they were about 75'-100' above ground and a good 125'-200' to the west, the Tejón's were some of the noisiest models I ever <EM>tried</EM> to use there. A final site I tried them at, however, had been a challenge to some models but the Tejón I hunted with there worked as quietly as any Tesoro I ever used there.
In short, it is just about impossible to know for sure unless you try a particular make and model at a given site. There are generalized answers, such as the Tejón was usually noisy around most power line challenges, but I didn't use them where YOU want to hunt so I can't say for sure.
<EM><STRONG>Monte