I think most people are doing RAID-0 to get more perf out of EBS volumes
"His results show a single drive maxing out at just under 65MB/s, RAID 0 hitting the ceiling at 110MB/s, RAID 5 maxxing out about 60MB/s, and RAID 10 “F2″ at under 55MB/s."
Summary source: http://www.nevdull.com/2008/08/24/why-raid-10-doesnt-help-on...
Data source (google cache): http://webcache.googleusercontent.com/search?q=cache:Vscz-VX...
You need to do RAID-10. EBS volumes CAN and DO fail.