Hi,
The server side synch doesn't require a separate service and a computer to run so in that perspective it's easier to manage. When I have been talking to MS employees they recommend the server side synch for various reasons, one being that the new outlook
thingy will rely on the server side synch to work.
One neat feature is that email (obviously), appointments and contacts are syncronized without the user having to have an outlook going so if you create an appointment with a couple of you work mates they have the appointment pushed to their calendars even if
they are offline.
That being said, the issues I've been facing with server side synch so far has been that it stops working at times and there is no telling if it's working or not, with the router you at least have a service that you can monitor.
Hope this is what you were looking for!
Rickard Norström Developer CRM-Konsulterna
http://www.crmkonsulterna.se
Swedish Dynamics CRM Forum: http://www.crmforum.se
My Blog: http://rickardnorstrom.blogspot.se