I have a client who installed the Splunk App and Add-on for Okta last May, but they are completely different from the versions currently on Splunkbase (as of Dec 2015). Everything has been re-written with all new inputs, sourcetypes, field extractions, etc. The Okta app itself went from version 2.0.1 last May to version 1.0 now, which is rather odd.
So what is the upgrade path? It seems to be a complete replacement, which is problematic since many custom reports have been developed by the client based on the old app.
Why is there no information about this in the documentation?
These are two different apps. (the old Okta App and the new one you see on splunkbase). It was taken down from splunkbase and replaced with the app and the Splunk add-on for Okta that is supported by Splunk.
The dashboards in the new app should have the same capabilities that were in the old one in addition to few additional ones.