Ok it was the passByValue in the ReplyTo that was causing the ClassCastException I resolved it by
removing the "passByValue" extension from the EPR ReplyTo
and added a new extension to the same EPR which yields "true"
If there is an easier/less hacking way to do this I would appreciate if anyone can point me to it. By the way this is currently only been identified as an issue for the InVMEpr or my service I haven't tried with JMSEpr or any other as such.