with respect to "Difficulty upgrading to newer releases":
pg_upgade has a --link option which uses hard links in the new cluster to reference files from the old cluster. This can be a very fast way to do upgrades even for large databases (most of the data between major versions will look the same; perhaps only some mucking with system catalogs is required in the new cluster). Furthermore, you can use rsync with --hard-links to very quickly upgrade your standby instances (creating hard links on the remote server rather than transferring the full data).
pg_upgade has a --link option which uses hard links in the new cluster to reference files from the old cluster. This can be a very fast way to do upgrades even for large databases (most of the data between major versions will look the same; perhaps only some mucking with system catalogs is required in the new cluster). Furthermore, you can use rsync with --hard-links to very quickly upgrade your standby instances (creating hard links on the remote server rather than transferring the full data).
that is all referenced in the current documentation: https://www.postgresql.org/docs/current/static/pgupgrade.htm...