I'm going to do the same job next week. I've already upgraded other release like B7331, B7332 and we have encountered few problems.
On the upgrade guide there is a section which explain you 'what an upgrade preserve'. In XE there is a new tool named Visual Compare. It's a good tool to migrate your application/report code from old release to the new. If you want contact me for your job, my email address is firstname.lastname@example.org