If we're just talking about Calendar/Contacts/Notes/Tasks, you can actually use Yahoo Calendar for exactly this.

Yahoo offers "Intellisync for Yahoo" which syncs Outlook with their calendar product. You can effectively have an infinite number of Outlook instances that synchronize data.

I use it to sync my personal Outlook with Calendar/Contacts/Notes/Tasks from work. That way I can enter something in any location and as long as I sync everything up (which just takes a few moments) the changes propogate through.

It also allows me to display my basic availability (without details) to the public by pointing them at the Yahoo calendar.

As far as reliability...well, I've been doing it for several years now without an issue.

Steve