Any drawbacks of using Hibernate EntityManager (vs. Hibernate Core)?

Question

The Hibernate EntityManager documentation states, that:

You may use a combination of all three together, annotations without JPA programming inter

Answer 1

I like using Hibernate Core directly. I also prefer XML mapping files.

I'm not really interested in using a secondary layer, to access Hibernate core functionality. As far as I am concerned portability in the persistence tier, is a complete non-issue.

There are very few real advantages of the JPA API over Hibernate API -- I saw people using JPA named queries (where Criteria would have probably been clearer & better), and the JPA annotations are somewhat better designed.

Other than that, JPA is just a layer adding complexity & potential overhead -- for no benefit. Architecturally in such a situation, the correct decision would be against using it.

Database portability OTOH is very real. I have custom allocators (generators) I use which are completely portable, and far more performant & simpler than the crazy mess which is the mis-designed Hibernate ones.

This approach has been very successful on multiple major commercial, Government & legacy database re-engineering projects. In short -- focus on what's important -- and an API on top of an API, is not it.