The Apache ActiveMQ 5.2.0 release goes a long way towards hardening the broker. There has been a particular emphasis on use cases involving large scale networks with high message volumes. The Kaha message store resilience has improved and the remaining issues around slow restart recovery will be addressed for 6.0.
The behavior or the broker and subscriptions in the event of slow or unreliable networks has also seen numerous improvements. One upshot is that failover in now included in the default brokerURL.
The resolved issue count has topped 200, so this release was a little overdue, but I think it will be worth the wait.