Hi, I actually have 2 320's, each with 2x 3TB Hitachi 5400x drives, but I have them set up as JBOD an one set to backup to the other, so I am pretty sure the RAID 0 will work. The the thing is that even though I have my set to back up daily, RAID 0, is probably not the best choice in terms of possible retreval of data. Yes I know you have the originals but, I am one of the "never too many backups" believers, and the other thing is that you may not notice any gain in speed with the striped option because the choke element in these NAS's is almost always the CPU, not the speed of the drives. But. that's just my 2 cents. Good luck.
PS. I hope you have already purchased your drives because in case you have not checked recently, the hard drives have more than doubled in price in the last few weeks due to flooding of the manufacturing area in Thailand.