One of my clients is in the process of standardizing all their servers on RAID 10. We discovered one of their smaller servers had been delivered with RAID 5 already configured. I took the opportunity to run some tests on the drives prior to reconfiguring them into RAID 10. My tests weren't very scientific. I just used SQLIO.EXE to generate random 8KB reads and writes.
This is a companion discussion topic for the original entry at http://billg.sqlteam.com/2007/06/18/raid-10-vs--raid-5-performance/