I am new to the Quattro. In the beginning, I bought this machine for just relic hunting bad ground in Maryland and Virginia. My other two machines, a Nautilus DMC IIB and a Whites MXT both have their own special attributes depending on where I am hunting. However, the Quattro is rock steady and I feel that it could compete with my other two machines when I hunt good ground. However, I have noticed in some head-to-head testing, both the Nautilus with the 10.5" coil and the MXT with the stock 9.50" coil go deeper and discriminate better than my Quattro with the stock 10.5" FBS coil. I am considering either the Platypus, the 12.5" EXcelerator coil, or 14" EXcelerator Searchcoil as I have heard good things about these products. Any thoughts out there?