But we're not competing with S3 directly as a general cloud storage solution. We're specifically focusing on the case of long term archival storage.
You can compare the two services as tradeoffs from the expression: Inexpensive, High Throughput, Low-Latency (pick any two.)
S3 picks High Throughput and Low Latency.
Nimbus.io picks Inexpensive and High Throughput.
But for bulk archival and restore tasks, does 100ms of latency really matter to you? In other words, are you equally happy if your backup/restore job completes in 2 minutes vs. 2 minutes and 0.1 seconds? Do you care enough to pay more than twice as much? So that's why we're focusing on the archival market.