You should have no issues upgrading your server to 8 from 6.5. The keys are to make sure you have the correct PTFs in place on the i/Series prior to beginning the upgrade, and obviously having a good, full backup done as well. I don’t know anything about your environment, but assuming you don’t have any custom fields/work done to the directory, you can simply allow the directory upgrade to happen when the server starts up and you will be good to go. The bigger project is getting your clients up to Notes 8 and giving them the new template. This takes a lot of planning and testing, as the requirements for the Eclipse based client (Standard) are far greater than the requirements of 6.5 or 7. You can always look to the Basic client, but it lacks a lot of the Web 2.0 features that the Standard client has.