Most of the Tesoros aren't that great for gold prospecting (nor does Tesoro claim they are as far as I know), that's why you don't see much online about that. The LST however was designed specifically for gold prospecting and under favorable conditions can find gold down into the sub-grain range.
Meanwhile, there are other good machines in roughly the same price range, particularly the Fisher "new Gold Bugs", and Tek G2 which is functionally the same thing. These machines are versatile and easy to learn, and you'll also find them useful for beeping the targets your E-trac and Prizm missed due to masking.
--Dave J.
PS: Before plunking down your money, I recommend reading my book "Gold Prospecting with a VLF Metal Detector", available online as a .pdf document on both the Fisher and Teknetics websites. Even if you wind up getting a machine that isn't a Tek or Fisher, at least you'll have some idea how to use it effectively.