Through the magic of the upgrade process, you don't have to worry about re-implementing notes. In fact SAP will list all the notes that weren't compatible with EHP2 that need re-implementation through the standard SPAU adjustment process. All the other notes should just flow through during the upgrade.
Note adjustments are straightforward, unlike the ui component respository comparison which is a pain, however the tools delivered in EHP1 and above make that process easy and not as bad as moving from 2007 to 70 where it was a major pain.
Take care,
Stephen