We are replicating with 2 x 4TB volumes and haven’t had any issues for over 68 days, though we are using DSS ver. 5.0_42 in block io mode.

Not sure if this helps others but on a side note we would have more interest in what Heimic and SeanLeyne stated then the 16TB replication option (DRBD+). Vkeven must be needing something other then what DSS provides currently or wanting blood like Todd said

Todd - any chance that we will see asynchronous soon (not asynchronious )?