At the risk of sounding not very sensitive and not very deep... "ARE YOU OUT OF YOUR FLIPPING MIND"???? Gain amplifies sound, but if you think sensitivity does not effect depth you are plainly mistaken. Try that theory out in an air test or a test garden and get back to us. It may seem that higher sensitivity is just increasing your signals volume however it is actually increasing the distance a signal can be detected and therefore given a louder report. Example.. the difference of a five inch coil compared to a ten inch, the signal volume is not becoming louder, the signal is just becoming stronger because the larger coil just goes deeper. In general, a higher STABLE sensitivity is going to produce better depth, period. In your test garden you may have some outside influences of soil mineralization, iron masking, electrical interference and or your own correct or incorrect coil technique, over discrimination etc etc etc. You are hereby asked to no longer watch poorly acted, overly dramatic soap operas or made for TV mini series as they obviously are contributing to your making an incredible, outlandish statement and then forgetting the explanation of your so ambitious findings, like a 1000 word dissertation would help, well maybe not with the statement "sensitivity doesn't effect depth"