Hillis would certainly know....I remember a F70 user who tried to get out of it what you seek, tried everything, back a few years ago, name of Goss...he posts up on the Minelab forum now, that's what he went with and he is happy. I'm sure I will buy another F70 one of these days if mine ever takes a royal dump. I talked to some old boys that have been detecting here in my area since day one, and if they were half as bloodthirsty as I am, which I'm sure they were, they got most if not all of the old silver coins in this area, sure, I trip across a dozen silver coins or so per year just doing my thing, but that is 12 out of a 10,000 coin yearly take for me, so its the old blind squirrel finding a nut reference..now these guys that post here and use the 75...that's a whole different matter, they really rack up the silver, but I don't know if it is as much the machine's depth capabilities as it is the location and knowledge of settings and coils that's doing it for them. I've resigned myself to hunt what I can get, focus on gold, and try to cover as much ground as quickly as possible, which the F70 or F5 are amply capable of doing. we both know if theres a silver Q or D within the top 6-8" realm, we will find it with either machine, I just don't know about the deeper masked stuff that seems to be what is left here anyway.. Let us know what happens.
Mud