Here are some tests of VRaptor ( Single and Raid-0) vs RAID-0 Devices.http://www.xbitlabs.com/articles/storage/display/wd-velociraptor_7.html
Note: RAID-0 generally does not help much. Usually helps more than it hurts but in some cases a small degradation is seen in RAID-0.
For performance, my money is on the Raptor.
For Value, its not the Raptor.
But if you are talking performance and the cost is not a concern, go for it.