Really nice write up. I'm curious if you guys have done any extensive throughput and latency benchmarking? I saw the note saying "ballpark figures."
FWIW, I've been working on a framework for empirically testing queue performance for scaled-up, distributed deployments (https://github.com/tylertreat/Flotilla). Haven't gotten around to adding support for AWS services yet, but would be interesting to see how they compare.