Has anyone had any experience with the Gold Bug 2 14" elliptical coil? I know most only use the tiny concentric so I was wondering if anyone's even used the bigger coil?  What would you consider the benefit to this coil on the Gold Bug 2?  Does it provide depth other coils don't?  Would it be beneficial to own?  I ask as it's now become quite cheap, dealers in the pacific region are virtually clearing it out at heavy discounts so I figured it might be worth snapping up before it's impo