I bought the DNS-320 along with the following drive, it has worked flawlessly on FW 2.02.
Western Digital WD30EZRX Caviar Green 3 TB SATA III 64 MB Cache Bare/OEM Desktop Hard Drive, JBOD, 3 Months. I have had zero issues thus far. My data transfer speed is limited by network configuration but I can hit 3MB+ with 802.11n connections. No issues streaming hardwired to the PS3. I am running ffun with Twonky media server.
For some reason the price on these shot up recently. I plan on buying a second 3TB and converting to a Raid arrangement.