I just realized that recoding the iDrive output to HiFi changes the output from line-level to balanced differential. There's no point in doing this for an OEM upgrade path like the Alpine HiFi upgrade kit-- you will have removed the "happy-faced" EQ curve but you would also change the output type to something incompatible with amplifiers that can't utilize a balanced input. This is where something like the Zapco SLDIN.BTL-F comes in, as you can just tap the branch audio connector under the seat and send a SLDIN cable back to the amp.
I'm planning a business trip to Portland in another month or two. Unfortunately, I don't plan to bring my car along but I am interested in seeing what you've done with your own car or customers' E9x vehicles. Maybe I could find a nice brewpub or diner and pick your brain for a few minutes.
