[heatmizr]

I have no need/desire to venture where you two have... however enjoy reading the write-ups.

On the "backward" button controls for PREV and NEXT song...
I am not sure which way the OP was describing as he did not specify, but CarFan you state:
"My up switch on the steering wheel does play the previous song and the down plays the next song -- which to me seems counter-intuitive."

The stock e70 buttons work as you describe - Up is PREV, Down is NEXT. The reason this is different from some other devices we use (like my BT headset I use when working out) is that when you are looking at the stock iDrive screen it lists the songs from top to bottom, so of course if you press Down, it goes to the NEXT song. Up goes back up one song. This is how I think of it so it makes sense when using those buttons.

It makes sense to me that these buttons are wired this way and continue to work in this way even with the unit installed.