For what its worth, I had an F75 from 2009-2011 that I loved, except when I was near power lines. It was noisy just like the rest of them (in discriminate mode). Then in 2012, I bought a Gold Bug DP, and that unit seemed to pick up virtually zero EMI, but wasn't quite as deep as the F75. Then, about August this year I acquired another F75, the black SE this time. I took it out to some of my EMI heavy spots, and sure enough, it was chattering like crazy. I was very disappointed, so I called a good buddy and asked him what I should do (possibly look into a new machine). He said to try it in the All-Metal mode..... Bingo! if you don't mind listening to the iron, this setting is AMAZING. Not only do I find it to be deeper than normal, but I love being able to hear all the iron targets. Being a civil war hunter, we all know how easy it can be to miss a little hot spot while we're out scouting if we miss that iron patch. It has made a world of difference, and it doesn't seem to pick up EMI very bad at all. In fact, on Black Friday I had a few friends into town to hunt with me, and was able to locate a fire pit by hearing the large iron targets that were mixed in with it, and it was literally directly beneath a power line that is unhuntable in discriminate mode. I had the sensitivity at 99 on the boost process when I found the fire pit underneath the power lines. (morelic55 will attest to the location of the pit)
Anyway, like I said, take that for what its worth... just my two cents, hope this helps
Here was one of the finds in the pit that day... Franklin Pierce pipe bowl