Sorry I didn't reply to your private email. Yesterday was busy. I really prefer to give answers on the JavaRanch, though where everyone can benefit from the knowledge.
I believe that since it's part of the
JEE spec, the JSF core class implementations are required to be provided by the server, so the answer is the same as for JBoss. Simply don't include the myfaces-impl.jar in your WAR and let the server provide the implementation. If you're
testing on
Tomcat and deploying on WAS or JBoss, you'll need 2 different builds (or to add the MyFaces implementation to the server lib directory).
I avoided the Sun RI for quite a long while, because it didn't seem to be fully functional, but the recent versions are OK, and some say its better than MyFaces. I haven't done any serious studies of reliability or performance, but I'm now happy with the Sun RI.