So after playing around with the tablet, I finally decided to get an "OEM looking" aftermarket head unit:
Pros:
1) Came with almost everything straight out of the box - was very impressed, given the price point: External mic, external GPS antenna, front dash cam, rear reverse cam all included.
2) Everything was plug and plug. I kept my original harness intact when doing the tablet/amp install, so there was not much to do in terms of rewiring. Biggest job was routing the rear view camera wiring.
3) Steering integration works perfectly as it came with a canbus adapter
4) Bluetooth pairing and audio streaming works without any issues
5) Comes with all the necessary cables you need, including a harness for the older "round pin" E39s.
Cons:
1) Whilst it came with navigation for SA, it was a pretty crappy application. Ditched it in favour of Google maps.
2) Even though you can customise the homescreen and all the button colours, some of the apps run natively in "Toyota" green.
3) The reverse camera came with a built in LED light (as part of the holder) - however, 5 mins after installing it, I hated having it different to the other side light (which was halogen), so I removed it. Not a fan of exterior LED on an old car such as this.
4) The mounting points did not align perfectly - had to do "massage" it to fit.
Some random pics in action - sorry for the crappy pics:
Also got to spend some time cleaning her during the long weekend - added 2 coats of King of Gloss wax. Here's some after pics:
And a sunset shot...