Sounds like my understanding must be out of date as of this year! (Which makes me very excited about your upcoming library.) My conclusion was based on research ~1 year ago finding no OSS or commercial software supporting it, and forum posts for those projects by developers sadly explaining why they just couldn't do multipart yet.
My bad experience with files disappearing was entirely with web-based POST requests, ~2 years ago. Large file transfer from EC2 to S3 was reliable, but our POST requests on slower connections (even those that were very reliable) would return with a false report of success.
My bad experience with files disappearing was entirely with web-based POST requests, ~2 years ago. Large file transfer from EC2 to S3 was reliable, but our POST requests on slower connections (even those that were very reliable) would return with a false report of success.