Head Unit - What will I lose?

I am looking to replace the head unit in the 06 FFRR and am aware that the current unit provides some functionality which I could not replace. I understand that I would lose the trip computer and clock, but is there anything more fundamental that would go?

All of the A/V and SatNav & Phone functions would be replaced by my new system (as would the clock).

Is anything else impacted such as fault computer etc?

Thanks

Mark.