Yes, In most applications, a VLF unit can be "pushed" a bit harder with more Sens in mild grnd. It is "ID accuracy" at depth that is most critical, as bad dirt is encountered,,,, and Sens is boosted. The higher the Fe concentrate.... the lesser the ID accuracy. Op Freq does matter; In general, a higher Op Freq will provide better stability and ID accuracy in bad dirt; however.....in general, at a lesser overall detection depth. Then enter another variable; "Depth" Vs. "Effective Depth". ....Bad dirt will attenuate EM energy quickly. Rob Peter/Pay Paul. Filtering adds more complexities; Possible enhancement for audible/intelligible data at a reduced/modified 'real-time' data presentation......possibly even losing data. On newer units...... yes, some filtering is digitally processed (mostly 16-bit....and rarely 32-bit).
P.I. = Should be the wave of the future (dry pun intended). However, I'd like to see us paradigm shift away from current electromagnetic-based platforms (and associated inherently flawed operating characteristics)..... to a different medium of detection (((and at a reduced cost))). Nuff said!
H.I.H.