You can still use the F75 in a place like that once you have used it enough to learn to tell the difference between all the chatter from the iron gits, ore, hot rocks, etc and the good targets. You can learn the difference, I did. You just ignore all that noise and pick out the signals. Also the F75 will quieten as you swing it. If you slow down it will get noiser. It will be noiser if you stop swinging in JE mode. I think lots of people don't use JE mode on the F75 because when they switch it over it begins to chatter, even with the coil off the ground,,, but it will quieten down a lot as you begin to swing it.
It's certainly not easy at first but once you get used to it "BAM"... you can hear the good target among all the junk signals and it will stop you in your tracks.
Still, I sold my F75 because I used the SE so much trying to learn it that I became used to the Minelab tones and couldn't go back the the squawking harsh tones of the F75. Besides, I have to stay with one machine a lot to be proficient with it. I can switch to a Tejon or Sovereign easily but I have to stay with either an Explorer or F75 as a main machine... not both, too much to remember, too much to be "used to".
Both the SE and F75 are good machines, both will drive you nuts for a while. The E-TRAC is much easier to learn than either of those.
IMO,
Julien