Make sure that the features you use are available in the new version. There has been some feature changes.
From my experiance I can tell you that I woulld work my way up to the latest version in the 5 family. Ten go to 6, it's latest version supported in that family and then to 7. There are a number of Backend database changes in the new version.
From a backup point of view. It might also be good to do a snapshot and a backup of your Master Server Settings. So that you could restore it if it goes wrong. Having snapshots of the ISM's as well to ensure that should something you could roll back.