No, do not pay them $200 to install, I am positive that the harnesses are the same, except for the bypass wire. Oh and I forgot to mention in the first post, The plastic connector for the GPS antenna is different, You can either replace the antenna or change the plastic connector, which is very easy, don't let that scare you. The reasons I did not like the F900bt was as follows:
1. No tracking Up in 2D navigation mode, this really bothered me.
2. Blutooth works, but was not nearly as clear as on the D3.
3. Maybe I was doing something wrong, but when your on the map screen, you have to hit 3 or 4 buttons to get back to the audio screen, i.e. ipod, xm radio, fm radio. ect.
4. When you pull into a parking lot, or maybe a dirt road, the D3 would track you no matter where you went, the F-series just gets confused and tries to place you on a road or the arrow just sits there and spins.
I guess that is about it, I guess it doesnt seems like much, but these things really bothered me.
I like the UI of the D3 better than the F-series, but since you prefer the F-series maybe you will love the unit.
I picked up an F-700bt on ebay for $250 and put it in my fiances 350z, and since she has never owned another navi unit, she doesnt have any complaints. Maybe when the 3.0 update comes out and I install it in her car, if i like it I might pick up another f900 to put in my truck.