Ive got a version 4 and don't have much trouble with EMI. Most of the "problems" that people have are due to running the sens wide open. If you do that, well yeah, it's gonna chatter. But even then the chatter goes away when you are USING the detector. Watch the videos, you'll see what I mean. For what it's worth, it's a pretty hot unit, and anything over about 65 Sens will get great depth and very little or no chatter. Mine chatters under powerlines, but so does my old Tesoro Bandido 2...and most any other detector.
I have the 11" Biaxial, stock 10" concentric, the little 5" DD and the 5x10" DD white coil. The 5x10 is the best of both worlds. If you are afraid of EMI issues, get either coil except the Biaxial and you will be fine.
I paid $400 for mine several months ago with the concentric coil. It's a little more than some have paid, but I got the box and all and it was like new. I have been very impressed with mine, and wouldn't hesitate to buy another.