General thoughts. How do we know for which services it's OK to do recursive chown on startup? I personally like it, but I think I've seen someone removing such code because on big trees it may cause service startup timeout. (Or otherwise an undesirable long startup delay.)

For services with a large amounts of files, we prefer static uids. Services usually fall into this category are databases, mail daemons or daemons maintaining media libraries. Also redis is a database, it does only maintain a single file for the database. When we upgrade to the next systemd version, we can switch to DynamicUser for services without static uid.