20KHz frequency effective?

[Billinoregon]

Asked this in one of the Nokta subforums, but thought I would ask here as well.
The Triple Score has three frequencies, 4 KHz, 15 KHz and 20 KHz the highest. I am wondering if this higher frequency would make the TS reasonably effective in searching for placer gold. Anyone know? I realize a dedicated gold machine and coil will do better.