Add that their flat rate pricing is actually a discount for moderately heavy users. If you use half or more of the 1 TB on the pro plan you’re already saving money compared to S3 pricing.[1] This is easy to do if you use something like Arq to back up your machines and take advantage of selective sync to archive rarely used files from old projects.

[1] S3 at 0.023/GB/month * 500 = $11.50