At a previous employer, we've migrated a complex J2EE (with EJB 2.0 and such) E-Banking system to use only Jetty and JDBC directly. No one in operations noticed the difference.
But the developers did. Oh they were about 5x as productive afterwards. With no missing features.
Perhaps I'm not included in the target audience. But if E-Banking can do it, what remains of the "target audience" ?