great news!

Good plan.

The E53 Avin4 android head unit is almost identical in appearance to the factory head-unit. I'd go ahead with the upgrade and enjoy modern tech in a factory looking encasement. When the avin4 is off, an untrained eye would be very hard pressed to notice it's not the E53 factory head unit.

+1 on the Avin unit. Looks stock to anyone that isn't familiar with the e53, but it gives you modern capabilities. I swapped mine and am very happy I did. I kept all the original nav equipment so if I ever sell it and someone wants the original for some reason I have it. Can't think of any reason they'd want it though. Nothing rare about a 3.0.

I didn't go with a stock looking unit. I wanted a bigger screen. I was concerned it would look weird but to me it looks like factory install

I have the Avin unit on my 3.0i and I love it. Smart of them to include the i-BUS app so it works with the DSP.

On this car I'm going to go BlueBus I think. Like my M5 I just want to keep it stock looking. I"m not pressing this car into daily duty (that's what my 3.0 is for) and for some reason I'm feeling very precious about keeping this car as original as possible. The factory screen is minty clear, so might as well just keep it.

Consider adding a BlueBus unit to give yourself streaming and great bluetooth capabilities in the X. It plugs in where the 6Disk is located in the rear left. I still have a completely stock head unit/audio system but now have all the upgraded BT that I was hoping for. I'm quite happy with it and it was very reasonably priced. It was also created by a member here.

Yes, BlueBus has been pre-ordered from ECS.

Who is the member? I actually have a question for them...

I believe @t3ddftw is who you're looking for

The bluebus is the only way to go in my opinion. If you want a massive ugly screen then buy a new car but for these keeping them as original as possible is the best way to go.