i was using it for a bit, but now for some reason with the v4.3 its not working for me. It worked well, although i didnt try to load test it, i think downloads are sent directly from s3 so i'd imagine it should handle just fine, not sure about uploads though as they may be uploading to the site then get transferred over but i could be wrong.
Multiple direct file servers is probably still the better option though. Maybe Adam can explain this though, he's the expert on this subject.