As a current owner of vehicles with and without nav, I'd suggest getting the OEM nav if you can afford it. I've owned two different versions of OEM nav systems (1999 and 2005) and I've owned two different manufacturer's portable devices in the same time period. Additionally, I have experience with Honda's system, as my in-laws opted for it in their Odyssey. In my assessment, it's well worth the extra $600 to have the convenience of integrated navigation. You won't be distracted by a display on your dash and you'll spend less time fumbling with wires and programming the unit. Furthermore, you'll have the added convenience of voice-activated controls for the nav and stereo.