Yours is an aluminum head versus the 300D's cast iron head. The aluminum is less forgiving to being run hot (I wish I could find a cast iron head for the E320
On my 300D all I did was remove the head, have it magnafluxed, cleaned, replaced the valve guides/seals and machined. Reassembled everything and since that time I do not have a pressurized system overnight. The car started and ran great prior to doing this and I did not have any overheating issues.
I think on yours the radiator being replaced should raise a red flag. I hear tell that there are places that can determine if there are products of combustion in the coolant reservoir.
It is my opinion that these cars can continue to run good for many miles with a coolant reservoir that remains pressurized overnight BUT on the same hand I am unsure of what long term damage, if any, may be going on with the head.