Sold the D2 off my V3i shortly after getting it so there's a vote for not getting the D2. Coil choice really depends on what you're looking for and where you plan on looking for it. Soil mineralization also plays a part. I live where there is very few old coins so most of my hunting is for clad and jewelry. The D2 gets good depth but for clad and jewelry it comes in about 5th or 6th on my list of coils for that situation. The Eclipse 5.3 is a get coil for trashy areas and it gets very good depth for its size. For even trashier areas the Eclipse 4x6 get the nod. The Eclipse 950 is a good all around coil for larger less trashy areas. It pinpoints well and gets good depth. It also works better than the D2, most of the time on saltwater beaches. Your S12 is probably best suited for farm fields and relic hunting on wide open areas. A top performer for recent coin and jewelry drops is the BigFoot made by Applied Creativity but it's no longer being made. Check the prices on used BigFoot coils, and you'll see that the demand has driven the prices to $350 - $500 (new they were $200). The HotFoot (also out of production) is great for competition hunts and fresh drops in very trashy areas, not much depth (3"- 4") but great seperation and super fast pinpointing. There's a lot of factors that need to be addressed to determine what coil is best for your situation. With more info, we can give better recommendations.