On my new 85th anniversary F75 9.0 is slightly deeper than 9.1. At least in an Air test. I tested indoors and I didn't have any Emi in either mode.Both modes were just as quiet but I didn't change frequencies to see if it got any more noise.I was on 99 sensitivity all the time with no noise. Completely quite.Defaut is F1 on mine. I got about 1 to 1 1/2 more inches in 9.0 in disc mode. All metal mode on mine IS deeper than disc mode and locks on to target better and Id's better. I don't know if Dst really goes completely off or on but mine Is slightly deeper in an air test with 9.0.
Ronk
Ronk