I have my 343 up and running with no failures for two weeks.
I moved 750GB of data back and fourth, deleted it, and copied it back. Rock solid.
I am using 1.02a beta firmware for the 343 to allow for the 1.5 TB disks.
I updated my seagate drives, model ST31500341AS, and upgraded to the 1B firmware.
I still only got 94% when I initially tried to format raid 5 so I pulled the last drive and formatted
3 drives in raid 5 array, then reformatted all 4 and it worked.
VERY Happy.
I also tried the Hitachi drive that are posted not to work and they don't.
They did, however work in my 323.
Good Luck.
I like my DNS-343.