[bell]

i've been a technician in this field for 11 years (mobile video/audio/security) and have played with a good handfull of navigation units.
i think that the alpine dvd based unit is the best out there, it uses the flip out style monitor and has a separate unit for the dvd map. the alpine wires into your vss and reverse wires and also uses the satalite for accuracy, as most of them do, but i found that the alpine is accurate down to less than 10 feet and thier map is VERY thorough. most of the navigation units have simalar features but you will find that the most of flip out monitor will be VERY close to touching your dash of your 911 when flipped out and it can cause "visibility" problems because of this.
i have not played with the beccker unit though, do you have any info on it?
hope this helps