I'm reading the latest version of getting started guide for dm server and I'm enjoying it a lot. It's very clear and didactic.

There is just one thing that bothers me. Is there a particular reason why Greenpages is based on EclipseLink JPA and H2 instead of more "standard" ones like Hibernate and MySQL for example? I guess there are very good reasons, but I'd like to know them as it might influence my technology choice for my first real dm project.

In particular, are those technologies mature enough for a real project? I mean not like HSQL that tends to be used only for development and demonstration purposes because it's easier to set up.