Sorry, but you are wrong. Judging something before trying it is like saying a duck can not swim without seeing it. I have simply told as well as showed my experiences so far and no one is forcing you to try or purchase one. If you owned one and were saying the same I may be paying attention, but.... Anyway it is cheaper than a bass boat.
I have now found over 30 nuggets in the few weeks I have owned this detector and most are from areas worked with the machines you mentioned as well as other PI detectors and the gold was still there! But now it is mine and a couple are pretty darn nice ones. The 6000 will hear gold the 7000 missed and there are plenty of Aussie and US users showing just that at YouTube and elsewhere if you take the time to look. In the mid and small nugget range the 6000 hears what the GPZ 7000 could not and yes I own both and know this by experience.
Discrimination on a PI is not doable with any accuracy on a PI detector and that is why it is not on this one or the 7000 due to the technology, they had a sort of discrimination on some early Minelab PIs but it was just a breaking threshold type and was not reliable and even discrimination on a VLF can cost you nuggets if using it while hunting.
Cheers and good hunting, Bill