We use a SSO method that was developed in house and matched with a customization from Jive Professional Services. In our implementation the profile data from our website serves as the master record and updates Jive upon every login. Any of the fields that come from our website are read only so the users cannot modify it within Jive, and instead have to change it on our website. As a result we don't have any out of sync issues. I will mention that this along with some other things we do on our website via API calls results in our Jive counted PVs being very high in comparison to what GA reports every month. Unfortunately there is no report or easy way to tell how many API calls we make each month contributing to this vs ones that come from within Jive (What Matters stream, etc). Do you know if SAML SSO uses API calls? I would assume, but am not sure.
Just a thought, no idea if it works for you and the users: Add an iframe/Ajax call to Jive in your portal, so the user will login also in Jive.