Although I am in the process of moving away from Backblaze, it's not because of this. Rather it's because they don't provide the flexibility I've come to need for prioritizing content to backup, and when I recently ran into a problem after swapping out hard drives, the error message Backblaze provided was the most unhelpful piece of drivel I've ever seen. --I was told to contact support with the error code "horse" rather than just being told that it was a timeout issue!
*Yev from Backblaze here -> Yea, that code was very early and was intended for support to gather data from the field as we were collecting data on what was causing the timeout, the message was to prompt folks to write in so they could collect some additional information. We'll probably be changing it in the near future!