I've prospected with the tejon quiet a bit.
Though I have not had much luck, I don't blame the tejon. I've dug up plenty of lead ( It's suppose to give a similar response to gold); and from what I have dug up, I have come to conclude that the tejon makes a fine VLF gold detector. I have dug out lead shards so small you have difficulties identifying them while even on the palm of your hand. After carefully researching a gold equivalent, I'm confident to detect a quarter to half a gram at about a maximum 3 inch depth (all metal mode, primary disk, sensitivity 8, slightly posi-tuned).
However, the stock coil will be useless for prospecting in mineralized soil. You will be frustrated at digging up the ghost signals detected by your stock coil. If you plan on hunting on desert, mountain ranges and the like, I would highly (HIGHLY) advice you to get the wide scan 5.75"
You have to set a primary objective. Are you going to restrict yourself to prospecting or are you going to coin shoot/relic hunt? Unfortunately, gold is mostly found in mineralized soil, and VLF technology is not the most appropriate technology for prospecting.
If you are going to be a dedicated prospector, you're better off getting a PI unit. PI units handle mineralized soil much better than VLF units.
Having said that, be aware that prospectors (notice that i use the term "prospectors," not "detectorists!") find most gold nuggets the size of a match head. A gold size equivalent to a match head is less than a quarter gram. And most detectors will have a difficult time responding unless on coil!
I have not tried detecting this minute size with the tejon. Still, speaking from experience, I would expect the tejon to detect this at a shallow depth of about less than 1 1/2 inches, which is still very competitive compared to many of the units currently in the market.
One last thing I should mention is the limitation of the PI units.
I don't claim to be an expert. I have no experience with a PI unit. However, from what I have read, PI units primarily detect the bigger nuggets deeper. They are able to "see" through the hot rocks and minerals much better than the VLF detectors. In other words, you'll still not be able to detect the really really small gold a good VLF detector will find (I could be wrong and please correct me if I'm wrong, but even White's TDI struggles with anything less than halft a gram) . So, even if you get a PI unit, you'll not be detecting most of the gold that would be detectable by a good VLF detector (at a shallow depth, of course).
That's why I would recommend both, a PI unit for the bigger, deeper nuggets, and a VLF, for the smaller, shallow nuggets.
Note: the size of the nugget in the picture is 1 gram.