> When I worked at an ISP, we slammed about 20 Gbit/sec into S3 without issues, but even then data we were backing up -- about 300 TB of data a day -- at that rate took 1.4 days to upload to the cloud, so we ended up backing it up in-house instead. (we needed to store the data for 7 days, after that it went bye bye).

Seems like the perfect usecase for S3; inbound transfer is free, and you're only paying for a rolling 7 day window of storage with lifecycle rules :/