Chiming in here too: no real issues with updating DB's / checking out a new version.
Definitley do a staging server first if you have a lot of plugins that need to update.
When we do a major point upgrade (EG: 5.2.X -> 5.3.X) there's always a few new things we have to add to our custom skins (IE New functionality / new objects skins) But a quick run through the system and they will be pretty apparent.