Hi
The Quattro has been part of my "fleet" for 4 years now. Although it got me a sore arm (tendinitis is not pleasant), it is probably the best damp/wet beach machine I ever had. The darn thing is a gold magnet, providing you know your beaches and know where gold is likely to be found.
Settings, well, it is also a matter of persoal taste.
The best setting to find a wide variety of targets is all metal, with -10 AND +40 notched out, low trash, and sens at 20 if the conditions allow. That is for clean patches.
In high ferrous pollution, I set the sens as low as 4 and still get good results.
Now, if you're at potential gold places, with sens at MAX and get an iffy signal, that is one where the ID number will jump BUT ONLY IN THE POSITIVE RANGE, check the spot with pinpont. If there is evidence of metal, DIG!!!. Now that will be (very) deep, and sometimes very rewarding.
Don't forget to noise cancel every now and then, it helps too.
A Helluva detector !
Grumpy