I haven't had a split brain on my 15 node cluster in over 6 months even though the cluster is split among multiple data centers which do drop connectivity from time to time. When the setting was wrong, it happened constantly. Tune it properly and it won't happen. n/2+1

Link for the curious: http://blog.trifork.com/2013/10/24/how-to-avoid-the-split-br...

True, that's a valid issue. For me, it's not as I end up indexing the same document multiple times over the course of 2-3 days.