Originally Posted by brianL
I've never encountered any problems after installing Guest Additions on any distro I've tried in VirtualBox. What problems, and where have you "heard" about them?
Same here. In fact many things are very difficult to do without
them. Think of the guest additions like the hardware drivers on a real system. You might be able to skirt by with the kernel's built-in ones, but things will work much better with the real drivers.
Anyway, you should be able to use ntp for this. I believe it has a special flag you need to set when the time change will be bigger than a few seconds though, which is probably why it's not happening automatically.