Are there any suggestions as well as the Pros and Cons concerning which Coil Works Best based on the different Soil Makeups at Parks, Schools, Older Home Sites or the Beach? I already have the Stock & 6" coils. Is it worth the extra money to purchase the 17" DD Coil? Also when using the CTX, what type of harness to take off shoulder stress caused from the detector weight along with swing repetitiveness would be the best to purchase? Any suggestions for these questions would be greatly appreciated.