I have a Quattro.
I bought a Quattro last year.
1. Get Andy Sabich's Book "Mastering the Quattro", Great Book. I have read it several times now.
2. Slow down. The Quattro is a great machine, but it isn't a speed demon. I think most people that give up on them don't take the time to learn it, and never slow their swing down.
3. Test Garden. Knowing what you are over, and how deep, is probably the best thing I ever did for learning mine (after Andy's book).
The Quattro will play you a symphony, and when you get started it will confuse, and sometimes infuriate you.
4. Turn down the sensitivity when you are getting started. This was huge for me. When I turned it down off auto, to 12 or 13 to get started I started being able to pick out coins and small objects sooooo much easier. It didn't change the depth nearly as much as I would have thought either.
5. Get a small coil. I got a 5" Sunray coil in August. The Quattro's biggest weakness in my opinion is how it handles in trashy areas. (Hence the Safari) Using a small coil had me picking out coins in areas that had been pounded for years. I set the sensitivity at 15 and picked out IHs and a semi key date V-nickel in an old fairgrounds that has been pounded by dozens of mders for years.
6. Be patient. There is a learning curve to a Quattro. This has defeated more mders than anything else. When the light comes on in your head, slowly at first, you will love the machine, and be finding deepies that nothing else has ever touched.
Good Luck.
Mark