In general, S3 should be as efficient for the registry than EBS, and far more operationally easy (it also scales out horizontally).
I don't know whether the encrypt option is done on the registry side - have you compared running with or without?
It's currently fairly difficult to move between backends - it's possible, but there's a lot of manual work you'd have to do. I'm sure someone in the ecosystem has written a tool, but it's probably not efficient.
On Jun 3, 2016, at 8:21 PM, Andrew Lau <andrew andrewklau com> wrote: