Get a PI machine Deere than any other vlf or bbs machine
The deepest I've ever dug any coin; silver, copper, or any other metallic coin was 10 inches in high black sand, and that was with a Garrett Deepseeker when I dug up several very crusty ones back in the early 70's, and in all-metal. So far, that is the deepest land detector I've ever had my hands on, with the Tesoro Tejon coming in at #2. However, the Tejon is mostly a boat anchor when used near the ocean shore, it just plain sucks. In adverse conditions of high Fe, the Fishers since then have almost consistently done best under extreme conditions, but in Texas for example, nobody needs to pay more than $500 for a detector, because minerals there are almost non-existent, especially on the Gulf sand beaches. The Garrett 2500 reportedly has the deepest all-metal ever made. I tend to believe that, but it's not a good one if the soil has too much iron in it. Here is some depth to (consider), and the F70 matches it for depth in most soils, and in high mineral soils too. If I ever buy another Minelab, I might get a 705, but I don't trust Minelab because of its too-frequent customer service complaints:
www.metaldetectorreviews.net/detectors/175-1-fisherf75.html
Almost forgot, I have also been looking at some used Fisher CZ's, especially the CZ5.
The CZ5 is coil for coil as deep as any detector out there. My friend buried a 9 inch dime at a church where we hunted for a while. I took the CZ5 out there yesterday and with the 8 inch coil it hit the 9 inch dime with a two way strong hit and a correct ID. I could raise the detector 1 to 2 inches over the target and still get the two way hit and a correct ID. That is with the 8 inch coil. I don't have a 10.5 inch coil but I am going to get one soon. I have owned an Etrac, XP Deus, DFX and others and none of them could find coins any deeper than the CZ5 coil for coil. Some may argue but I am speaking from experience and many hours detecting with other units.
Hey Pescadore
I have the 10.5 inch coil for the CZ5 and to be honest it makes the detector feel heavier than it already is. Only used it a couple of times. I find the stock coil more than adequate and use it most of the time because like you said it is deep. The 5 inch coil is deadly for trashy areas.