tried this out today in my test area. very trashy place, my yard! set my sensitivity to 2(mx sport), still had good depth, I have reject at 50% so I can hear all the junk, found a copper penny in a hole alongside a nail. id'd the penny. also found a rototiller blade about 10 inches down, (one tine, about 8 inches long, shaped like a knife blade if you've never seen one). most importantly, the machine was easier to use and more civilized I guess. not sure how to phrase it.
I'm not sure, but I don't think you need sensitivity up very high to get good depth. but correct me if I'm wrong. I also go to a local park where the machine is super noisy and jumpy, I'm going to lower my sensitivity there and see how it goes.