Thanks Simon. You were right.. I forgot that I had overwritten the TestOperation setOutputType() call to effectively no-op, so I wasn't building the response correctly.
I'll share one thing I did learn (in case someone or myself has to search email for a problem like this in the future). By running with the IBM JDK, you get an "orbtrc" trace file, and by adding this to my maven command line: -DargLine="-Dcom.ibm.CORBA.Debug=true -Dcom.ibm.CORBA.CommTrace=true" it gets a detailed trace with eyecatcher. This let me see pretty clearly that my "app" data wasn't in the "bad" IIOP payload..just the header/context/etc. info. Scott