I've got a MacBook Air and an iMac on my desk at work, both running Yosemite. If I upgrade the MBA to El Capitan, will my calendars, contacts, etc. still sync between the two via iCloud? I recall when I made the upgrade to Yosemite, I had to update both computers or the data wouldn't sync. I can do the MBA upgrade myself but have to call IT in to upgrade the iMac, which complicates things!