the V1 and Passport8500 are pretty neck and neck in head on detection. but the V1 is more sophisticated with the directional arrows and rear radar antenna, although, the passport can pick up rear signals(due to the plastic casing), but you have no way of knowing if its comming from the front or rear. the Passport also comes with a smart cord (which is kinda of like the V1's concealed display) and the detector can operate in dark mode to not draw any attention. the Passport also has programmable band defeats which allows to deactivate any band, good for eliminating false alarms (most new V1's have this also, but you may have to send it out for upgrade). the Passport also has a better display screen which can 1. tell you the exact frequency of the radar, 2. display each band individually showing radar strength, or 3. 'expert' mode which can show you every band at once along with their frequency (good for reading multiple threats). the Passport can automatically switch between highway and city mode which can adjust the radius of the detector and sensitivity to also help eliminate false alarms.
both passport and V1 have bogey counters and safety warning systems, but its the V1's rear antenna and rear arrow that pull in the most buyers