Hi JT,
There have been several postings about using the GQ for nugget hunting. One of my latest was on Dec 30. So, you might want to do a search covering the last year or two.
There are several differences between the GQ and the ML GP, but the main one is the GP has ground balance as does the SD's. This will make a big difference in real bad ground.
Overall, the GQ is a good nugget hunting machine but it is ground sensitive, meaning the ground will cause a positive signal. So in some places, this can mask a weak nugget signal and make the detector more difficult to use.
As far as sensitivity, the GQ will detect as small of gold and in some cases smaller gold than the SD's, but the GP will outdo the GQ on the small stuff by a little.
You might also want to read the posts about the Detecting Invisible Nuggets, posted on Dec 25. It gives an idea of what might be possible if a GQ is pushed to the limits. Obvously, this isn't available at the present and probably won't be for a while. However, one who is knowledgeable and has the proper test equipment might get one to detect small nuggets better than other PI's presently made.
Just a thought.
Also, if you are into electronics, then you could build a DD coil which helps tremendously. A properly working DD almost eliminates the need for a ground balance in most places I hunt in AZ. In fact, that is about all I use now.
Reg