I installed an X910BT in our car about 8 months ago and have been generally happy with it. We just bought a second car that I will be using primarily for commuting to a new job and I'm not sure I can live without the iPod, Bluetooth and nav functionality of the 910, but I can't justify the price of installing another one in this car.
From what I've read on this site and others, I don't think I would be happy with the U310, so I'm now leaning towards a used or refurbished F700, F90 or X710. So I'm asking for confirmation on my thinking and other recommendations on comparably priced units with the above functionality.