Using Adobe LifeCycle Data Services ES instead of BlazeDS gives you some extra features like security, WSRP portlets, data push or data synchronisation between the connected flex clients and you can generate PDF documents with LifeCycle. With BlazeDS you can only retrieve the data from the application server. With LifeCycle you can also do CRUD operations on this data and the best part is LiveCycle Data Services ES Express has been free for a single CPU server.
To use LifeCycle in jdeveloper you have to create a new web project and copy the lib and flex folder of the flex.war to the WEB-INF folder of the jdeveloper web project. Do the same with the web.xml. We only have to add some java options to the run configuration of the web project and we are ready to run it. Add -Doc4j.jmx.security.proxy.off=true -Doc4j.userThreads=true to the java options