I take a slightly different approach. Google calendar is my main calendar and this works across devices including my Android phone and tablet.
However I use the old-fashioned emacs diary, which org-mode of course easily incorporates. Diary is simple to work with. When I start up emacs, I use gcalcli and some custom elisp to fetch my Google calendar and regenerate the diary file completely, every time. On exiting emacs, I run a diff (through custom elisp) to find changes to the diary file and again use gcalcli to push those changes back to Google calendar. I don't try to sync contacts or notes bidirectionally. I do use mobileorg to make sure my tablet/smart phone has a copy of all my org-mode stuff. If I do happen to edit on the tablet/smart phone, it's a manual process to put that back to the master, but this is not my usual working mode. I have a lightweight laptop (Asus Zenbook) and carry that whenever possible. Overall I sync to and from a master at strongspace.com, which supports use of rsync. I suppose some day I should get away from diary, but it works really well. -- Bob Newell Honolulu, Hawai`i * Sent via Ma Gnus 0.14-Emacs 24.3-Linux Mint 17.2 *