I had the hidden K-40 unit in my previous car, and I thought it falsed far too often, even in the "CITY" mode. I ended up shutting it off in the city, and just turned it on for highway trips. The warning range also didn't seem as good as my Passport 8500. While I admit it is nice just having those two little LEDs flush-mounted in the dash, the negatives of the functionality outweigh the aesthetics (and I do HATE having a box on my windshield), in my opinion.

I have had a k40, valentine 1, and now a Passport 8500. The Passport blows all of the other ones away. Much fewer falses, much more functional, more capabilities for expert users, and totally undetectable (tested by local law enforcement.)