Hi David, I replied here before I saw your PM. I've had the Gold for about 7 months. I'm not a serious prospector- I've taken it out to some gold producing areas a few times, still learning that part, though. I can't say that I use the threshold very often - just once in a while when I am re-checking an area that has produced some nice finds and is pretty cleaned out. That puppy is sensitive!!
The ATG works well for me because it seems that everywhere I tend to hunt is absolutely paved in bits of rotten, rusty iron of all sizes along with the infernal aluminum caps and tabs and sardine cans (must have been THE staple food of miners and the later homeless folks). The ATG has 44 points of iron discrimination, and I sometimes use and appreciate them all. The 5x8 coil, on either machine, is a godsend - it has enabled me to hunt areas that I had attempted previously and written off as un-huntable. The soil here is pretty mineralized - gb is from 75 - 93. In practice, I don't really notch out segments on the AT Pro - the 'coins' and 'zero' presets are fine. Likewise, on the AT Gold, the "Disc 1" is pretty similar to 'zero' and 'DIsc 2' is pretty similar to 'Coins". I also just like the sounds of the ATG more.
Bottom line: The ATG is the one that goes in the car & the ATP is my excellent backup machine. I had to send the Gold in for repair recently (user error, I cracked it off the shaft). While it was gone, the ATP found me enough Gold to pay for itself. If I had to choose one detector for my conditions, I'd buy the AT Gold ( I don't hunt salt water) - but, it would be a near toss-up. If you have milder soil and cleaner hunting conditions and / or like to notch items out, you might prefer the AT Pro. I just feel like the ATG does everything well; a world class prospector, relic hunter, and coin shooter.