I'm curious about what is behind Moz's statement "The business impact is profound. We’re spending less and have improved reliability and efficiency." I don't have the experience with large AWS setups to comment about the cost implications, but improved reliability and efficiency strikes me as questionable - AWS's reliability has improved markedly over the last 18 months to the point I cannot remember when their last…
Moving to your own hardware lets you actually reason about what's going on in a controlled environment, and at the scale that Moz is working at allows us to get hardware that's robust, well-supported, and reliable enough to have a pretty serious net positive overall.