The new (4.2.1) behavior is more predictable, but it breaks backward compatibility with old packages that have broken requirements specifications (i.e., missing specific epochs when they're needed). If we want to move Red Hat 8.0 and 9 over to the new behavior, we could make new mozilla, etc. packages that work properly with RPM 4.2.1, however.
This btw is why I am sad that Matthias, to this day, refuses to add explicit epochs to versioned dependencies in the freshrpms packages. It is so apparent that this can lead to real problems later, so much so that even Red Hat began doing this recently for their own packages. This particular policy has been strictly enforced by fedora.us for a long time now, but unfortunately has been one of the emotional points of contention that caused certain key contributors to not join fedora.us.
(Just to be clear, this is not a personal attack on Matthias. His great work at freshrpms.net is what inspired me to create Fedora in the first place.)
Warren