The secret to the Sovereign is learning it well, I have always said that the ones that design the Sovereigns know how it will work the best. That said I bought one that had a mod from someone done to it and tried it out and found the tones were set so most target sound higher pitched, it was silent search also so there was not threshold or had to set it up higher. The ones that I had was the XS series and the GT series has the switch for silent search that I can see where in some cases it is OK. On my test I did with actual targets in the ground in my test bed that was made around 1980. Several of the coins I didnt get a reading like I did with my reg Sovereign GT I had. Maybe it was a bad mod that was done by some, so I sent a very nice Sovereign to someone I trusted that knew the mods and checked it out before I sent in my test garden and wrote down the spec to compare when I got it back. Right off I notice the tones sounded higher pitched, had to turn up the threshold to hear the threshold, I feel the threshold you have to hear to get the depth as it cant break the threshold, also in iron you never know when in a null you can not hear the coin next to it.
Any way in the test garden I notice I lost depth, couldnt tell the zinc pennies from the copper pennies as the tones sounded the same. I open up the control box and seen the tones were set to max and the threshold was also set to max, so with my good Sovereign I was able to compare the tones and the silent search to keep them the same and did the test again and I got my ID better and the the depth the same. I think that those that thought it gave them more either swing the coil faster and miss those iffy signal on good target close to iron or a null of the detector.
This was with the XS series of the Sovereign I had been using since 1996 and got a GT when they come out which I still have with the SunRay 180 and the S1 probe, but haven used it for a few years because of health problem and the weight is too much now for me and if they ever make a light weight Sovereign I will be the one I will get, and save my GT for a spare. I think many of them that learned the Sovereign and know what they can do still have them in reserve.
This is my experience I had with the mods while others may disagree. Maybe someone is doing mods I dont know of and doing something more than maxing out the tones and setting it to silent search.
Rick