Any metal detector will pick up gold if it is big enough size. As you go up in frequency you detect smaller gold, and the same big gold with the other machine will usually be detected deeper. Example, Minelab Sovereign with 5 inch coil will pick up a man's gold ring I don't know 5 or 6 inches. A half-gram nugget maybe one inch deep or less. Since I have an AT Gold I know with the 5x 8 dd coil it will pick up the same ring at twelve inches. The smaller stuff about 1 grain you might only get three inches in bad ground. So the other thing to consider is that aluminum tabs, even wadded tight foil sound like gold. But yes, the gold machines are going to hit harder on the low conductors compared to the coin machines.
There's a lot more to it than just how hot it is on gold. Target separation, recovery speed, etc. not to mention the specific features for working in iron all add in to the final blend. Then you have to decide which machine has the features you need.Of course you will get propaganda and snobbery not to mention outright deception from a couple MFR's. The internet is a good place for that. I have no doubt the MD designers are tracing the electronics in the AT Gold right now so they can copy it. You think these MD designers are genius, well they just copy the latest thing and change it enough so they hopefully don't get a lawsuit.