How well the Detech will work in comparison could have a great deal to do with the dirt. It certainly has a great deal to do with trash and noise.
The Detech does not like trash and noise. The S-12 is surprisingly good in these areas for depth and target seperation.
In clean and quiet areas the detech easily beats the S-12 (in my dirt). You have to watch the sensitivity setting though.
There is a max setting for best performance that can be very sharp and clearly defined, particularly in dry dirt. Even if conditions allow settings higher than the 11 or 12 o'clock peak (depending if it's on the 2a or the GT), the depth will drop off quickly and the target response will sound bad. I think this happens because the ground noise being picked up chokes the Sov to death and renders it unable to clearly pick out the target signals.
Another thing about it....Gives solid hits a lot like the Minelab coils. It either hits or misses, while the S-12 is more prone to threshold jumps without target audio on weak targets.
If I am getting a little noise and the threshold bounces around a little I can ignore this with the Detech, but will wear me out checking out all the spots where the threshold jumped with the S-12.
Another odd thing....
Let's say you can only run sensitivity up to 12 o'clock with another coil before you start having trouble. You will have to set the Detech about 3 hours lower to get the same stability. At this point I don't think there is much if any advantage to the Detech. Works best when conditions allow the higher settings that I mentioned earlier.
You love them or hate them.
HH