In particular, online calendars tend not to feature pop-up reminders, and those that do don't do as good a job of getting your attention if you're doing something else. Even if you install extra software such as a Notifier or Messaging application to pop-up a reminder, the pop-up window only stays on the screen for a few seconds and then disappears. If you were in the loo when the reminder popped up, when you return you'll have no idea that you've got an important meeting in 59 minutes. Pop-ups reminders from online calendars also tend not to offer a snooze feature, delaying the reminder for a while, which is something I find invaluable.
So that's why I'm sticking with iCal on the desktop, but I still want an online fallback when I'm away from my MacBook. I'd say Google Calendar is one of the best online calendars and Googling for "sync iCal Google" leads you straight to Spanning Sync. Now that it's out of beta, Spanning Sync costs a very steep $US65 (or $US25 per year).
Before I went any further I made a bakup of my calendar data, and I suggest anyone following down this path do the same. The problem with any kind of sync is the risk of duplicates, so it's the first test I use to separate the wheat from the chaff. Unfortunately Spanning Sync didn't fare very well. Syncing iCal with Google was easy enough, although the lack of a progress indicator is disconcerting during the initial big sync.
I created an appointment in iCal and it appeared in Google, then vice versa. So far so good. Next I moved an appointment in iCal by an hour, from 2pm to 3pm, but after the sync it appeared in Google at both 2pm and 3pm. I thought another sync might fix this, but afterwards it appeared twice in iCal as well.
As someone who is regularly shuffling around appointments, Spanning Sync's duplicate problems are an immediate deal-breaker for me. Another issue is that Spanning Sync doesn't sync reminder alarms, instead appointments inherit the default reminder settings from their target calendar. I can live with this, but it might both some people. I'd perhaps pay the high price tag if it did the job and was my only option, by there are a few other apps to consider first. CONTINUED