Actually... I've had previous positive experience dealing with some parts of JEE and some parts of Spring from almost zero (just knowledge on Servlet and JSP) to production level (JAX-RS, JAX-WS, JPA/Spring-Data/Spring-Transaction, Spring-Portlet-MVC, Spring-Core). They just seem to ... "work out of the box".
Had two production issues in a year and they are all JPA.
From all of the modules, JPA seems to be the more complex piece of the puzzle with EJB/JMS probably trailing. (Granted we did not have to use JMS yet).
While I do understand your side of the story (you may be aiming for JEE full-stack from JSP, JSF, Servlet, JPA, EJB and tons of its quirk, JMS, transaction, etc), if you focus to the essential: JEE 6 web-profile, it is much easier compare to starting with Scala from zero to knowing best-practices and idioms of the language.
Agreed, but before JEE 6 web profile, essentially all before JEE 5 was much much harder to work with. Deploying a basic demo EJB 2 app on some ancient JBoss took our team of "enterprise developers" about two weeks. I'm just saying Scala is nothing exceptionally more complex than many other things that are or were used by so called "enterprise developers".
BTW: on the last training in databases I led we used Scala as a language in which some sample programs were created. The group was not specifically prepared for that. Actually they were even not all Java developers. They had no problems in understanding Scala code and modifying it for the purpose of the excercises.
Had two production issues in a year and they are all JPA.
From all of the modules, JPA seems to be the more complex piece of the puzzle with EJB/JMS probably trailing. (Granted we did not have to use JMS yet).
While I do understand your side of the story (you may be aiming for JEE full-stack from JSP, JSF, Servlet, JPA, EJB and tons of its quirk, JMS, transaction, etc), if you focus to the essential: JEE 6 web-profile, it is much easier compare to starting with Scala from zero to knowing best-practices and idioms of the language.