4 kHz and full tones is definitely a winner, even if you've gone over an area previously using 8 or 12 kHz. Iron rejection is better, you get a slight bit more depth on silver coins, and those iffy targets are more "resolved" in 4 kHz I think. Small bits of aluminum are ignored but copper and silver targets "pop" much better vs similar sized aluminum pieces, unless its an aluminum coin or token.
So far with the Deus, 4 kHz to me is the best frequency for ferrous vs non-ferrous determination. Deep iron still gets me from tome to time, but sometimes after pulling out that large iron target there's a coin thats been hiding doesn't that is now screaming to get discovered!!!
I like the VDI spread on 4 kHz as well, most of the time its accurate enough to Identify silver from clad dimes and quarters, which is more than enough resolution than I'd ever need! But remember that co-located iron can pull down the VDI a few points. Fringe targets sometimes raise the VDI so careful with notching! The best example of this are round pulltabs at 6" will often ID like coins which is a nuisance...round pulltabs won't have consistent VDI it will be jumpy, and the audio will be a little "off" don't know how else to describe it.
Keep hunting you're bound to fond more keepers!
