Maintaining a production DB containing 15-25M rows show best improvement with the use of RAID0 on EC2 platform. Having a MySQL master-slave replication of servers and keeping the documented procedure is very handy for restoring the DB and the RAID volumes.
Documenting the process on downgrading and upgrading RAID0+MySQL from large to xlarge EC2 instance or vice versa helps a lot.
The links below best describes the RAID0 performance for IO operations on EC2 and how to setup the EBS RAID0 and MySQL in your machine.
IO Performance on EBS
EC2 EBS SINGLE AND-RAID VOLUMES IO BENCHMARK
EC2 EBS RAID
mdadm: A New Tool For Linux Software RAID Management
Running MySQL on Amazon EC2 with Elastic Block Store
EC2 Consistent Snapshot
Using Maatkit to restore Slave-Master
Auto MySQL Backup