TBH, the current revisions of 2.0 (i386) are extremely stable once you configure it properly for what you need. I've found that most of the revisions add little things but the benefits are tremendous over 1.2.3.
Personally, I've been on the Aug beta 4 builds in production environments and haven't seen a need to actually upgrade. Everything works except that RRD queue graphs are shot once the shaper is reconfigured. A removal of the queue graphs and refreshing of the RRD script fixes it and since the traffic shaper is almost never reconfigured once it works, that's fine for me.