only scanned the replies, didnt read them in depth.
i personally use full tones -6.4 discrim. whether my theories are accurate or not? who knows!
i like to think it gives the machine better performance because it is not trying to figure out if it should be iron or not (probably not true, but let me believe it)
also, it gives you all the information you can get out of the machine. which to me, is important. i want to make the decisions of whether or not i dig a target, not let the machine decide for me. i want as many clues as i can get, and having the entire range of audio gives me that.
now that being said, i hunt some sites that have iron under every sq inch of the dirt. sometimes i actually use relic with IAR and notch out everything (within a few #'s) that i am looking for.
so my answer to your question is yes. its worth it, but obviously depends on where and when you want to use it.