Het lijkt me wijs om eerst de optie Archief > Exporteer > iCal Archief te gebruiken in de "oude" iCal vooraleer de nieuwe versie te installeren...
Overigens is het volgens Apple zelf nodig om elke agenda afzonderlijk te exporteren...
Zie
http://support.apple.com/kb/HT4226Important:
Do not rely on traditional methods for backing up calendar data, such as exporting the iCal database, Time Machine, MobileMe Backup, or iTunes backups of iOS devices. Any changes to the data in the cloud will be more up-to-date than data in those backups and override a restore done from those backups.
Backing Up Data
To create a reliable backup of your data while using the new MobileMe Calendar, you must be syncing your calendar data with a Mac (iCal) or PC (Outlook). Here are the ways you can back up your data:
Back up using iCal (Mac OS X v10.6 Snow Leopard required)
Open iCal.
Ensure your data is in sync (up-to-date).
Select one of the calendars in the Calendar list.
Choose File > Export > Export.
Save the file to a safe location.
Repeat for every other calendar you want to back up.
(Bewerkt door Johan Morris om 20:28, 15-10-2010)