I decided to start a separate thread on this rather than hijack the thread which generated my question.

I always used ferrous sounds (and liked it) on the SE, but I used conductive sounds on the E-trac. For those who use ferrous sounds on the E-trac, how does that work, and what is the rationale? Given that the Fe number of most good targets has been standardized to around 12 (theoretically) on the E-trac, how would ferrous sounds allow you to differentiate between the different good targets? And wouldn't that drive you crazy for really deep targets where the Fe number is really bouncy?

Or is it just a focus on identifying all good targets by tone, and then looking at the Co number to tell more about what the target might be? Maybe I've been thinking about it wrong.