Can I use the SQL object features with a JDBC 8.1.x driver against an 8.0.x database?
No. Even though the 8.1.x JDBC drivers are backward compatible to 8.0.x databases, they require an 8.1.x database to support SQL object features. In a configuration using an 8.1.x driver and 8.0.x database, you might be able to compile a SQLJ application that uses SQL objects, but it will not work at runtime.