Morning Steve
When I had my 4.4 I replaced the standard set up for 2 reasons first the Nav unit was flaky and the TV was analogue so no signal. After a lot of research I went for Dynavin. There were many cheaper available but most came from China and had dubious or no back up. I also wanted to retain the OEM look
The Dynavin unit gave me excellent radio, Digital TV, Bluetooth, Nav etc etc and retained the OEM look. It did need the 5m extension lead running from the main radio quadloc connector in the boot but that is straight forward. Cost back then was about £500 from memory but I sold the OEM stuff on Ebay and recovered most of that.
The new models I believe integrate with OEM DSP and retain the OBC functions