I have the same snooper in my car - it's pretty good. IMO, all snopper / radar devices suffer from some degree of false alarms - mine will pick up traffic lights, MWD door sensors etc etc. It's also no good for those new blue cameras that use sensors in the road.
I've been thinking about buying one of the new GPS devices, which has ALL the locations of all cameras programmed in it, along with a GPS sensor that know where you are - you update it by plugging it in your phone line. That plus the snooper will give warnings of all speed traps. I've heard good reports about the Origin Blue GPS unit.