Originally Posted by iluvmybonnie
you are better off putting in an aftermarket nav unit. much high quality, better maps, options, etc. you can buy one used for the same price as those you are seeing on ebay used. 0 headache or worrying about if it will work, better quality etc. it'* basically a no brainer use an aftermarket unit it'* leaps and bounds ahead of the stock gm ones. if you don't believe me go read a review online there are many which compaire stock vs aftermarket. aftermarket destroys stock in every one. this includes bmw'* nav and others nothing can touch the aftermarket ones.
While aftermarket nav units are generally more "feature-rich" than OEM, you've made quite a blanket statement here. I'll assume you're trying to compare apples with apples (ie: in-dash units, not an in-dash compared to a windshield mounted unit). I'm not sure how you justify no headaches or worrying about if it will work. Virtually every in-dash aftermarket unit will have integration issues requiring one or more additional modules to retain functionality with OnStar, steering wheel controls, XM Radio and the warning chimes. Selection needs to be based on what the end user is trying to achieve. I had a TomTom and really liked it. I hated the "aftermarket" look and distraction of having it stuck to something on my car. Although my in-dash unit has fewer features, it gets me where I need to go and "plays nice in the sandbox" with all my OEM equipment.