I too am a beta tester, and we've been running our renders through a queued render farm for a couple of weeks now. The faults have to do with the combination of a brand new licensing scheme and the switch from flexLM to SPM.
Before the recent change in the license scheme, SPM was performing far more reliably than flexLM. For example, flexLM was notorious for systems frequently loosing contact with the license server due to network synchronization problems. We were rebooting the server on average once per day to deal with this. SPM didn't manifest this problem at all during many months of the 2.0 beta cycles.
The new licensing scheme appeared out of nowhere, and the change has lead to some SPM problems with serving out the right numbers & types of licenses. This, combined with some general limitations of windows networking technology, has resulted in some consistency issues with our render queue system (the same issues aren't showing up for Linux render farms). In other words, our render clients still require some vigilance.
I expect these SPM issues to get resolved quickly. Otherwise, everything is looking really promising regarding XSI and render farming. MR3 is fast, batch mode starts into renders immediately (no more mi file conversions if you don't want 'em), and the stability of heavy renders has improved substantially.