I have both. The AT-Gold is used for the Goldfields (All metal + Threshold ) or Park hunting, AT-Pro Beach or Park. The biggest difference for park hunting for coins would be the coil size, the signal on the ATG with the 8x5" is much tighter and makes it a lot easier to tell the difference between a goldie (NZ $1 or$2) and the likes of a new twist top it's also great for trashy areas. With the 11" the click at the edge isn't as prominent and I find I dig a heap more trash BUT I find the deeper silvers far easier and you can cover more ground quicker. If I had to choose one or the other I'd probably go with the ATG reasons would be All Metal Mode, I don't hunt the beach very much and I don't notch. In saying that as I'm more concentrating on the park not the playgrounds at the moment I tend to pick up the ATP to cover the bigger area, once again that's simply because I can't be bothered changing coils over - Or if I hit a trashy area my wife usually isn't to far away with the ATG. Hardcore users might disagree but I don't think really there is a huge difference.