Hello Leif,
thank you for your deep diving into the world of calibration and ColourSync.
The secret behind ColorSync the profiles you can create for every appliance individually .
So you build a trustable chain in Color Management.
To calibrate the monitor there are now cheap versions of the professional on the market. I have and use the Spyder2 - please take a look here:
Spyder3Express - Datacolor - Global Leader in Color Management Solutions
With lovely greetings
the Wilfried