There are some pending fixes to network taskqueue, callout, and some thread based packet handling. Until those are adequately reviewed flip the default back to acquiring epoch in ether_input(). This should be a minor performance penalty that ensures that no more broken drivers are encountered for now. Conveniently someone abstracted flag accesses so that I only had to stop drivers from unintentionally clearing the value in one place.
We have discussed this with a subset of core and we believe this will take some urgency out of the situation so that a more healthy technical discussion can take place.