Very intresting reading your article, because I thought I would be the only person installing another OEM BMW headunit and not going towards the aftermarket way. I am pretty sure the CD 43 was a different internals to the radio I installed, but they have the same connections and asthetic design. I chose to install another OEM bmw radio because there were no HU out there that fitted the rest of the car like that radio.
The radio I pulled out was a really old bugger was the poverty radio that came with E30's E28's and E34's had a tape drive lcd screen and no cd changer options....and the thing had only 2 channels left and right which was then split by the fader control switch.
So got the radio out of my mates '99 M3 and got the code from the stealer. But the speakers in my car were pretty stuffed and they were 8ohm and the HU is designed to work with 4ohm speakers so I replaced all the speakers with some phillips 80w ones. I am not a person for cutting and splicing wires....I HATE IT so i was searching throgh the ETK one day and came upon an OEM adaptor that was a plug and play to convert the old plug system to the new "rectangular" plug system. So yeah it was fairly bolt in...except the harness i got was designed for the wireharness that had the HU that had fader control on it rather than having a fader switch. I tapped them in so the fader control switch still worked because its easier to use that going through the menu on the radio.
So yeah everything plugged in fine. then i bought a stacker and got an E36 stacker harness and wired and bolted it all up per factory design...
And yeah it does me quite nicely. Having your HU would have been really cool...but i sometimes plug my laptop in via the tape deck so yeah that has its advantages also.
Great work though I like your thinking