Gil, thanks for the nudge!
I was able to login using the 4.11.2 client after creating a new database and restoring the xtuple quickstart backup for 4.11.2. Worked fine.
I tried again with my own backup file and saved the restore output to a file, the errors were:
language "plpgsql" already exists
role "pgsql" does not exist
I created a pgsql role, tried restoring again and no more errors about that.
I saw that CREATE LANGUAGE was deprecated after postgres 9.1 and extensions are used now. I used the pg_restore list options to exclude the language plpgsql line. Since plpsql is already an installed extension on my installation, I figured it didn't need this line. Now the backup restores with 0 errors.
The ERROR: function compareversion persists when trying the 4.11.2 client.
I probably need to update the database, but the updater, both 2.4 & 2.5, are giving me the same ERROR: function compareversion.