Nobody will store their data _now_. If in 2-3-5 yrs it's proven to be both durable & highly available (I'm looking at your maintenance windows, B2) I don't see

Nobody will store their data _now_. If in 2-3-5 yrs it's proven to be both durable & highly available (I'm looking at your maintenance windows, B2) I don't see a lot of reasons not to move away from S3 as this should be plug & play at this point. There will be edge cases for highly regulated businesses of course, but for an average startup why not?