Hey Cal... I was swinging over 4" of snow last year, scrubbing along, and learned that some amount of air between coil (2-3") and ground seems to work better than scrubbing, I dont know why, but have been doing it ever since. Definitely better separation, way much quicker, great signal strength, as far as depth, I dont know, you F75 guys are looking for targets deeper than I, but I do get some finds in the 8" realm in wet chip totlots especially after theve been re-chipped, and its easy diggin, on wet beach sand often. In the dirt, not so much, but there I'm just clad stabbin anyway. If there happens to be an old silver in the top 6" of soil, no doubt I'd hear it. I think the general consensus is the F70 is wicked great for targets in the top half foot of soil, and maybe with proper conditions and set up, might get 8-10" on coins... F70 w/11"dd strength to me is quick brooming, and thats a different style and way of looking at soil covered per outing...it can be vertical soil covered with a hot machine looking deep, or horizontal soil covered real fast...both have their merits and places.
Mud