I just want to buy it once and be happy with it, i don't want to spend money twice if once would be enough.
The Gold Bug Pro is only sold with the 5" coil where i live, and that's way too small to effectively search a big area. So that's not going to be my detector.
I wanted to add the Makro Gold Racer may be one to consider. I have all but the little round coil. The big 15" does a great job to cover large areas and I've found stud earings. The smallest elipitical has excellent response to very small gold. The difference I find in this gold detector is it's ability to have a clear, distinct response to gold that is as small as 1 GRAIN. A half gram nugget would be a very distinct signal.
As long as the target is within the detector's ability to show VDI numbers you can see the target value.
The whole point is, when looking for gold, you dig every target. If you cant even tell or hear the target, you won't dig. Gold detectors are high frequency in order to make a better sound when you do pass it over small sub gram size gold. Lead is almost the same response as Gold on the VDI.
I use the large 15"coil and the concentric coil when hunting for rings/coins. These two are great for fields.
I use the 10"DD and the 5"DD for gold as the response is crisp on sub grain Gold compared to the 15" coil and the 10" concentric. Since I want to know if there's a target, I need to hear it. And sub gram size gold is not "visible" with some detectors.
So, in reality, what it really means when they say, gold detectors see gold better, it means, a small target will give a more crisp response.
You say you want to see VDI numbers to reject trash? Well, the VDI will give you what it "thinks" it "may" be. Your ear can hear even better what it may be. So, it's necessary to use both. Practice with a size of Gold that you are trying to find. Put it along side trash. Try to tell the difference. Even put it under trash. You will find that your detector will see all of it and respond. It is up to you to decide to dig. I believe you will find, There's no way to accurately decide which is what. That is the nature of "metal" detecting for Gold.
So, a Gold detector will see ALL the tiny bits of ALL metals if you are using it like a gold prospector would use it.
I hope this adds to your information. It's a challenge finding Gold. That's what makes it so interesting. I hope you find some!