I am thinking of getting a large coil for my Etrac and know that there has been lots of discussions on the various ones but was wondering if anybody has done any testing of the large coils side by side such as the sef,nel,coiltek in the 12" to 15" areas or larger. Seems like going to a 13" wouldn't be that much bigger (deeper) than the pro coil so I am not not sure which is the better way to go. I know there are lots of different places and styles of hunting and no 1 size fits all. I am mostly after something deeper than the stock pro coil to hunt cleaner areas for older coins only. I do like my little sef 6 x 8 as that has been a great coil but don't know much about the bigger ones. It does seem to make sense that bigger should be deeper and I want to make sure I am not missing anything. Maybe somebody can chime in and thanks.....Just toooooo many choices out there...