I came to the F70 from an F2 so for the first few months I mostly used 4H because it was most like the 4 times of the F2...except for the high tone nickel thing.
Results were a much higher nickel volume than I usually dig, a whole bunch of clad, several older, deeper coins and all kinds of great stuff.
Next I ran with 2F for awhile because I was hunting in some woods on top of a small mountain that had some pretty good EMI and I read that 2F is affected less than the higher tone choices.
It worked great, I was hunting areas that had been recreational horse trails so but a of iron everywhere from nails galore to horseshoes to bigger.I
The iron tone was informative and it stayed at low volume so I could listen to it without being bothered.I
Turns out the three lowest tone choices are the best for high EMI sites....1, 1F and 2F.
I rarely use 3F because I just like 4F better, 1F comes in handy in some sites where modulation helps, the tone choice I ended up using the most is 1, monotone.
I found that monotone with the disc down to 1 or so gives me information and I mean a ton of it constantly.
After much practice, (and I mean many hours), I learned to deal with it all and process it to my advantage in the red clay mineralized iron infested mess I hunt.
It just works better for me than any of the others.
DP....I have used it and kinda like it, could not get the hang if it at first and I just switched to it for a few minutes here and there to get used to it.
Over time...and again I mean lots of time, eventually I could tell the tones of a lot of coins by sound and pick out some fleeting sounds that help me find some pretty masked targets that could have a lot to do with those 99 tones...or not, but I dug some great things in DP.
Still nowhere great at DP, though.
https://www.findmall.com/read.php?37,2378302,2378348#msg-2378348
Despite all of this and the fact that I have explored all the tones for enough hours to understand them pretty well and a few to even deeper levels if you catch me out there chances are I will be in all metal.
Works even better here than monotone.
In great dirt everything works, in rougher dirt I found some work better than others or for me they do...everyone is different.
Just try them all and you will find out which ones you naturally gravitate too and will enjoy the most.