I was thinking about the IOPS that you can sustain with this type of device, and as mentioned here, this is intended for backup, which may or may not be very good acting as a filer.

Probably you can get some high IOPS with all these drives in parallel, but probably not as much as the other more expensive ones (EMC, Netapp).

But I have to agree this is an awesome setup optimized for a specific application. Way to go