Raptors have faster access times than other drives, but SSDs are about 50X faster yet again. RAID 0 doesn't really do anything to improve access times. For booting and starting applications (tasks where access times are important) going to an SSD would give you a significant improvement.
For tasks that are more dependent on transfer rates (example: reading and writing large files quickly as in editing video or large RAW files from digital cameras), RAID 0 can bring raptors close to the performance of an SSD, and you'd probably not notice that much difference.