I purchased my 8500 X50 (M4 I believe) last May and have liked the extra protection. There have only been a couple of times that I felt I had an "amazing" long range detect, but being my first radar detector, overall I have been satisfied. Until about three months ago my X50 lit up full blast on an X-Band hit while driving through my neighborhood where it is usually silent. I continued thinking it was a real source, but it did not go away. I had to turn off the unit and back on to get it to clear, I figured it was a fluke. Another month passed before this happened again, but in late February it happened three times over a two week period. I reluctantly sent my unit in for service two weeks ago. Last Thursday I received my X50 back, (very fast service IMO), but the first time I pulled out of the drive-way it hit a full blast X band. I drove 4 miles seeing if it would clear on it's own, but no luck. Now my 20 minute commute is interrupted with 3-4 non clearing X-Band hits. I called again for service, with "It worked when it left our facility" as an unapologetic response.
I have a long trip and worry the unit is offering very little protection right now.
For now X-band is off, but it was so quiet on X band before (maybe three specific points around town), I don't feel I should have to turn off features to feel that I am still protected.