You'll need to review using the "all" jboss configuration instead of the "default" configuration (if you're not already doing so).
If you're using the "the appserver owns the DB" caching policy (policy A??), you'll need to ensure that your entity caches are sync'ed.
Jboss has made this pretty easy to do, but you'll need to configure a few things in the various xml files -- described in the pay-for doco.
I believe that using the "appserver owns the DB" caching policy may offer the best performance -- if you can live with it's limitations.