2003 Lincoln Navigator Navigation

Hey Guys, im new here and thought i'd ask you a few questions to help me out. I have an 03 Nav with factory 6 disc changer. Its the radio with the cd button and not the SAT button so its the basic deck. I looked into the whole swapoing it out for the factory Navigation system and its a dead issue. I have asked around and not really worth it, too much work with a low success rate. So i said screw that and decided to look into the avic-d1/d2 or the avic-n2 First off i know you loose steering controls but can get them back easily with some sort of adaptor, i have seen it and its probably my best bet BUT what happens with the parking sensor? When you put the truck in reverse, not only does it tilt the mirrors down but it lowers the audio and you hear a beeping sound telling you how close you are to the wall and what not. Will i lose that? Can other who have installed either the avic d1/d2 or exlipse units let me know if thats the case. I was thinking, if thats the case, i might just keep the stock radio, get rid of the ashtray underneath it and drop in an avic n1/n2 and add it to the exeisting system. all i would have to do is feed the sound into the factory system by means of modulator or other adaptor system. Right now i have 2 tvs in the head rests and a dvd player plus a windows xp comp system with navigation and 8 inch touch screen, Its nice and all but i was something thats more built in and dont want to wait for it to boot up, too many switches, an avic-d1/d2 would definitly clean things up! Thanks in advance Ken

Voice controls are great, but steering controls are definitely more practical (ever tried using voice controls when the music is turned up really loud? its quite diffficult sometimes), and while I do love backup cameras, the reverse sensors are really good, I like using the old school approach of just looking over your shoulder when you're in reverse, and the backup sensors are handy in this case for making sure there are no small objects behind you (kids, cats, small trash cans) that you cant see through the rear view mirror.  Not to say these arent both great features, but there are definitely occassions when they dont COMPLETELY cut it for some people.  I have an 04 expedition myself and am about to put either the eclipes double din nav unit or the new alpine double din screen in there, and am quite curious about some of the questions you have asked as well, would love to hear some responses on this one.

Good points scarface.

Well there are some guys here who have switched over to aftermarket systems, Can any of you guys chime in and tell us if you still have the features or not?