Like I said, if you need to assemble your own app services, then Spring is a better choice, as each EJB 3 implementation is optimized for a special app server for better performance and user experience. But I disagree that unit testing is an advantage for Spring -- the new generation of lightweight EJB 3 containers makes in-container testing easier (and of course more accurate) than using mocks -- give it a try!
In the case of your Spring application, yes, you have managed to create Spring-independent "business service" classes (IMHO, EJB 3 session bean POJOs are a lot simpler). But I am sure your application as a whole still has various dependencies on Spring (XML and helper classes). You might be well justified to have faith in Spring vendor. But I am also right in claiming that Spring causes "vendor lock-in". :)