I moved to Linux a few months back, and was going to basically cancel my Backblaze sub when I got around to it since you have no interset in making a Linux client. Maybe B2 can act as a solution to this at a price penalty.
I can understand your biz reasons for not having one though.
My only interest in B2 is backing up for a lower cost than the ridiculousness of S3: at $0.022/GB, I might as well buy a 3TB hard drive myself, put it at a friend's and push my data there. Every month. At the end of the year, I'd have 36TB in hard drive capacity if I bought drives instead of paying for 3TB of S3 storage.
(All numbers are estimates and "roughly"s. Also I don't have external backups now because I'm too lazy to write the software myself, so there is something to say for paying instead of not having it.)
I use backuplizard for personal data/photos which works out more like cost of a one 2 TB disk per year to me and to me Its easy to pay it instead of owning disks and worry about them breaking,etc
All in all, it's by far the cheapest option to store it at a friend's. Storage providers could also cheapen things a whole lot by offering reduced redundancy and whatever else it is they do to make it so expensive (glacier storage is also more expensive than the price I got). It's a backup after all, I don't need my backup to have five copies on spinning (versus offline, non-powered) disks. If my backup dies, I'll upload it again...
It is faster transferring big files rather than many small files.