I have Mountain Lion and want to upgrade to Yosemite. I need to use iCal on my old iPad (iOs6). I heard Yosemite asks you to update to iCloud Drive (that can't be installed on iOs6/7) and that you won't be able to sync some apps until you update. Will iCal sync on Yosemite if you don't upgrade to icloud drive? If not, should I update to Maverick instead?
I eventually updated and checked myself, and the answer to my question yes: even if you don't update to iCloud Drive, iCal keeps working and syncs on your devices connected to the old iCloud.