What is the sense of comparing Multifreq detector to pulse induction? The last one does not have the possibility of low conductor discrimination... in the best scenario only high. On a clean patch that is kind of idea or solution.
Multifreq is a marketing trick of big manufacturers. If Multifreq is soo good MF detectors wouldn't have single frequencies. This video shows that in the air EQ800 is much better in air, but in the ground its depth drops dramatically. Many people test their detectors in the air and forget that the ground test shows true depth. As you said air is only just for fun and not prove anything.
deep hunter mobile st need to RESET at every 2-3 min. or more often . Golden Mask HF1000 it has a very stable operation, you don't have to touch the settings during operation and you are always guaranteed the same stability and depth.