Before any update, always take a backup of "stuff".
Today my contacts were all duplicated multiple times. Fortunately I had a backup (Outlook export file) and was able to kill and restore the personal address book on my desktop. Then did a one-way sync to the BlackBerry.
So in my case "stuff" above means Outlook contacts.
Theoretically the update process is supposed to backup your apps so if you trust that then I suppose apps don't need to be included in "stuff", especially since they can easily be re-installed (whereas rooting through a duplicated address book with thousands of entries is much more time-consuming).
