Is there a way to use Oracle XE as an easy-rollback "proxy" to regular Oracle
Oracle 12c Snap Clone feature would probably fit your bill. Via a self-service portal through OEM, your non-DBA users (i.e., developers) can spin up private thin clones DBaaS-style. Since it uses copy-on-write, it doesn't physically duplicate the source. Each clone just needs space for the deltas. End users can make snap clones off of a TB sized master in minutes and see when they are ready for use. The clones can quickly be deprovisioned and reprovisioned, which would take care of "refreshing" the private DBs when desired. Really cool stuff, but requires an experienced Oracle DBA and equally good &amp; patient Linux/Solaris admin to stand up this infrastructure, basically a private cloud.

UPDATE: although this requires OEM 12c, it works with Database 11gR2 &amp; 12c.  This 20-minute video from Oracle is illuminating:  http://youtu.be/J7fnfLS5Dxg