I hope you made out well today!
I'll try to contribute but I'm new to minelab, so take the following with a grain of salt. I've hunted an hour or two everyday since I received my EQX in February. When I get near lots of iron (cellar hole lip etc) I use park 2, 3 response (600), 1 iron bias. Usually around 19 sens. Away from iron I switch to park 1, sometimes I go to 2 response but mostly stay on 3 because I swing faster than I should (I've have thousands of hours on the T2 previous to the nox)...oh, and I haven't ever gone over 20 sens...it doesn't seem to need it.
I'm interested in your opinion with the nox coming from the F75.
PS Now that I re-read your post it hit me you're looking for relic settings...lol...sorry! My settings are trying to find coins amongst the iron. I have nothing to offer if you're trying to find iron relics.