And bharping, you make a good point about interrogating a potentially masked target at 28 khz or higher because even if the target itself is not a mid-conductor, the higher frequency can help separate non-ferrous from ferrous better because of the higher resolution afforded by the smaller wavelength of the higher frequency.
Regarding your program, looks great the only comment I would have is be careful about using the iron wraparound notch (at 97-99) for the hf frequencies (i.e., 28khz and above) because it is more likely that legit high conductors get pushed up into that TID range because their is no ID normalization on the hf coils. I have 14k pitch program just like yours (though I bump iron vol up to 3) with the 97-99 notch, then an identical one at 28khz but no notches.