I am in very similar situation, just bought W212 E63 and only found out that it has ghost when I went to collect it.
No paperwork provided as to what the system actually is or where it was installed
And due to me not being used to the ghost, sometimes I do it wrong and it just causes car to throw alarm, ignition and transmission codes when scanned afterwards.
I am actually considering trying to get approved installer to take the ghost out of the car, as in my opinion it's good when the car is parked in public car park or something like that.
But while it's on my drive, it's actually just another invitation for any potential thief to try get in the house. I'd rather if anyone tries to steal it be successful at it, and not put family at risk but hey that's only my opinion.