i have an 04 with factory navigation. I wanted bluetooth and Ipod support so I went for a Kenwood DNX7140. I found it a frustrating machine - very long bootup, about 15 seconds for the radio to turn on - reverse camera was sufficiently quick. The interface, however is a thing of horror - buttons are minute and you cannot get to them quickly, there are too many icons on the screens which you cannot setup, so that even if you don't have dvd gfilms, xm sirius , aux, hd radio etc, it insists on having two pages of sources to chose from to go between radio and ipod. Radio presets were also frustrating as the preset buttons would always disappear and it would take three clicks to make them reappear. Garmin navigation is solid,
In the end, wife constant unhappy factor meant it had to go. I bought and installed the newer factory unit E7008 but, because of my analog amplifier, i could not get full bluetooth support, so today I am about to install the JVC KT3HDT after some research
What attracted to me was - fast bootup, lifetime traffic support with no extra cost, iphone support with no extra cable/module, support for HD radio, POI upgradable for free via google. Detachable faceplate is usefull as i live i the city. SD card support so i can put mp3s directly on SDCards. Iphone support via bluetooth. It has one drawback the usb port is on the front - so if you want to control your iphone via the unit you have a cable hanging down.