Gunnar, thus far in my soil PP or all metal don't appear to be any deeper than discrimination, but I need to test further, but then again I'm so impressed with the depth of the GT with the stock 10" coil and especially with the 12x10 that I don't see any need to hunt in PP or all metal. Thus far every time I test them against each other discriminate seems deeper. In fact, I don't like to use PP mode to PP because often it won't even hear a deep coin that discrimination easily nails. This is in my somewhat mineralized soil, of course, which ranges from low to high depending on site. I've owned just about them all but this thing is the deepest yet. Also, machines with higher than about 8Khz (signal frequency machines that is) never ran smooth or got the depth in my soil. So it depends on what type of soil you have that you consider bad. Different "bad" soils can be of very different types than other "bad" ones, where a machine will do very well. For instance, I recently read of one guy who has some rather bad red soil, and he said of all his machines (one or two flagship models) the GT when ran slow will even null out a lot too in his rough ground, but darn if it's not popping him deeper targets than he ever saw before. Read many examples of this and have experienced it myself (owned most of whats out there). I think the BBS frequencies biased in the lower range in some respects below say 12khz (since they only range up to 25khz) are punching through my minerals like no other, and is the reason they get the depth and run as smooth for me on my mineralized beaches and land sites.