Does EMI reduce the depth capability of the F75?
In other words, if you're hunting in an area where there's a lot of interference and the F75 is real clattery (with the coil not moving), does the interference reduce or rob some of the transmitting/receiving signal (which would also reduce depth)?

I would imagine that EMI would reduce receiver sensitivity and therefore reduce depth.

True. And proportionately. The more EMI....the less depth performance. This is true with any unit.