Indeed. I wonder why people even think that "load balancing" with shared storage ever makes sense. The biggest bottleneck in server performance is disk throughput. Putting a bunch of fast CPU frontends in front of the same Bunch Of Disks isn't going to do squat for write rates, and write rates are the only important metric in a replication scenario.
I think perhaps the OP is asking the wrong question, sure, but I see a great need for the ability to provide a "load balanced" read cluster not for the performance gains (and there certainly could be some on reads) but for the HA. I'd certainly like to be able to quiesce a node for maintenance, take it out of the cluster, patch it, bring it back up and have it re-sync, then bring it back into the cluster without any interruption in service to the users. It looks like mirror mode in an active/active cluster (behind a load balancer) would allow me to do that.
John