I doubt that we have much gold here in Alabama, we're too far from the beach, and not much civil war fought here, so, that leaves coin shooting . However, we do have lots of iron in the ground (bad soil) and rusty nails. Will the GPX's, SD2200's or 2300's actually discriminate  iron good enough to be able to go a little deeper than my CTX3030? My CTX is good for about 4" in worst soil and 7" at best. I need something to get a little deeper. The only PI's that I've owned is the original TDI sever