Sorry to be late to the discussion. Had not been to the forum in a couple of days. That being said, I do have a Vista Gold and an RG 1000 V2. The gold is 25 khz and the RG 1000 V2 is 12.5 khz. Both are very deep machines. The Vista Gold is slightly better on gold rings and jewelry and much better on the tiny gold chains. The Gold is really hot on small brass cuff buttons for relic hunters also. At 25 kHz the Gold is amazingly stable around high EMI areas such as power lines. The iron volumn control is a great help in old nail infested sites.
The RG 1000 V2 is an all around hunting machine. Slightly more depth on a nickel, about an inch in my soil and a good two inches better on a dime and a quarter. It is a bit smoother and more forgiving in changing soil conditions.The RG 1000 V2 would be closer to a Smart. The Smart is 15.5 kHz. I have not gotten to use a Smart but would think they are fairly close in reactivity to targets. The basic rule of thumb should be, the higher the KHz rating the better sensitivity to small gold and lower conductors,and smaller metal objects. These are all great coin and jewelry machines on dry land and in the dry sand at your beach.
Now in the wet salt sand. They are single frequency machines. There are far better options for wet salt and water hunting. I tried the Vista Gold on the wet sand at Virginia Beach and Myrtle Beach in S.C. They have some moderate black sand on both beaches. The Vista Gold will not work on either beach. Again the higher the frequency the closer to the conductivity of the wet salt sand you are going to be and the more erratic the machine will run. If I am wrong on this point then please correct me because this is my opinion and nothing more through my experiences and what I have learned so far in my detecting learning curve, and I have a lot to learn.
On the wet salt sand the dig it all pulse machines are great if there is not too much iron on your beach. Of the pulse machines that I own, the Sand Shark, Whites Dual Field, Whites TDI, and the Mirage PI made by Sven, all are good machines. The TDI and the Mirage are the only machines that run as low as 10us thereby making them much more sensitive to small gold.But the Mirage is by far my favorite for beach hunting. First and formost it is waterproof where as the TDI is not. Also the Mirage does not hit on most of the deeper iron that the TDI does. This is a great help at the end of the day. How he gets that out of the machine is a mystery to me still, but you will dig less iron with the Mirage. And last, the Mirage has a small gold or large gold setup switch to make the machine more sensitive to lower conductors and small gold or higher conductors and larger gold. It has some descrimination, but is not an Excal or CZ 21which have full descrimination, but they will not find small gold chains and gold crosses like a Mirage PI. I hope this helps....Stuart