I have used the Gold Stinger for about a year now, and dug thousands of targets with it. I don't have any nuggets in my immediate neck of the woods, so I only used the stinger to find the higher concentrations of black sand in the gold producing river through Edmonton, and that's where I panned for the flour gold. (the pic below is from many years ago of the flour gold I got in Edmonton, before I was metal detecting.)
So my thoughts are, it is an old machine, and it's been around for a long time. Garrett used the same Groundhog Circuitry in the present Stinger as it did in many other machines in the past because it worked well. Now it's not a depth machine by no means. You will have to spend a lot more money to get a machine designed for gold for greater depth, with the top end Minelabs going for over $4,000.00. So what you will get with a Scorpion, is a detector which will find match-sized gold nuggets and larger in lower mineralized soil down to about 4 inches, deeper if they are larger. If you want to get the nuggets which are deeper, you either have to hit a spot which hasn't had much prospecting activity, some luck luck or an expensive detector. The nice thing about the Scorpion is it's price, (will get you into nugget prospecting for less)it's Groundhog circuitry to assist you getting some iffy signals on gold, a manual ground balance to get even greater depth in higher mineralized soil, an auto-turn on and go for both true all metal mode/motion discriminate mode and finally a motion discriminate mode for general coin/relic hunting. It also has a TR mode, which some use to help distinguish hot rocks and also for ore sampling.
I have discovered that the Scorpion really sounds off on gold rings, silver rings as well as the older round aluminum pulltabs. It is the "BEST" detector I have ever used for Canadian clad, as Canadian coinage is made out of nickel, steel, zinc or steel. So, yes it's an older machine. It takes 3 x 9 volts (recharge ables work great) batteries, which can only be inserted after you remove the detector housing. But what you are getting is a good solid built machine, made in USA and designed to get gold and also works well as a coin shooter brand new for less.