ArcGIS Map Server Cache in Amazon S3

We’ve been loading our tile caches in Amazon S3 for quite some time now and it looks like others are trying to take advantage of the service. I’ve come to the conclusion that using S3 for your tile cache makes a ton of sense for performance and reliability issues. Our S3 tile caches are more reliable than our file servers in serving up the tiles and do it so much faster. Is anyone else noticing the benefits of S3 or has is been problematic for you?