Did a bit more research, it has been 15 years since I had a radar detector. With my ham radio geekyness I grasp most of the concepts so I was happy to see that Escorts passport max, max2 and max360 all use DSP and I believe FFT's. This would put them in a class of their own and I can justify paying a bit more for the technology. They have basically turned these into SDR's "software defined radios" or in this case software defined receivers. This would also explain why it took about 5 years after Mike Valentines patent expiration for Escort to come out with the 360. My guess is they were focused on the DSP which is far more important then having a rear facing antenna.
As an SDR presumably using FFT's the receiver in these units would be able to see entire chunks of radio spectrum in a single glance, rather than scanning through a band much like a police scanner does. This means it has near instant detection, its POP performance has to be outstanding. You can replicate this with a simple PAL USB TV dongle and some free software. You can connect this to a PC and see the entire FM radio band at the same time streaming down a waterfall on your PC.
Another advantage of this is the DSP portion, they would be able to essentially fingerprint signals. I am sure that is how they get so few falses, they can easily tell the difference between a real radar signal and the blind spot detection sensors. This also allows them to attach GPS info to a known stationary false and block it forever. I borrowed a cheapo detector last year from a buddy for a "fast run" to Chicago and back. For 30 minutes I was slamming on the brakes and then speeding back up, turned out to be a Porsche who's blind spot detection was setting off the detector.
Anyways, some might know this others likely don't. I just wanted to put it out there because its not documented very well, most publications and tests just call it magic in a box and don't talk much about the technology. If you are on the edge on what device to get like I was, $200ish for a used 9500ix vs $280ish for a used Max, hands down spend the extra money.