Under normal circumstances, that would have been a valid choice - RAID0 usually provides greater perfomance, but with a greater risk of lost data in the event of a drive failure.
The performance increase, which is greater on disk reads, results from the fact that you can be reading from one drive whilst the other drive may be seeking (moving the head) to a new location - and only occurs when the disk subsystem is the bottleneck.
Today's disks are significantly faster than those of a few years ago and so the advantages of RAID0 have become largely theoretical, and tests have shown that RAID0 on the DNS-323 provide little if any, increase in performance.
Still - my concern was for safety of your data - since RAID0 does increase the possibility of lost data, but, once you have it backed up, you're good to go.