One thing to be wary of with remote storage is that SQL doesn't know things are committed, and you could end up with an inconsistent database, especially if the transfer from your local disk to Amazon went down. I know some people that have had this happen with SANs when the SAN had too much stuff written to cache, and SQL was expecting those transactions hardened to disk. If the power drops or there's some issue and the data never gets written to disk, you'll restart SQL in an inconsistent state.

SQL is not recommended for remote storage. The disks must appear local, and I'm not sure this would be a supported config if you had issues and called MS.