Also if you are already using decent SSDs, then RAID 0 doesn't add much. You don't tend to get the queue depths in real life software to really push RAID.
Have you even benchmarked this?
I have, and it do add lots of performance. If you are running application X and it did not improve, that does not mean it wont improve for others. Running a MySQL server on an SSD will give SOME performance improvements, and some aspects will not benefit at all. Running a modern day database server will give you INSANE performance boost and you'll start seeing the network inferface as a bottleneck.
Also, if you are using a crap SATA2 interface with SATA3 drives… well <- that explains itself.
My advice for using SSD's is to get one and try for your specific case. If you can afford a PCIExpress based one that sits directly on the bus - They are AWESOME and yes you can put them in RAID too, i got 2 x Revodrives up to 2.8 GB/sec.
I'd recommend against using them as storage for reliability reasons (since they are new), but as a "working cache" where you only put your active casefiles/images, they are invaluable to speed and performance.
I use ssd's for the OS and temp image storage/file signature files, and sata3 WD RE drives for the rest, which improves the whole processing a lot. However, considering that ssd's are prone to