Agreed - there is a tradeoff that must factor in many things: engineer competency or the ability to get competent engineers, state of the product itself (maybe Elasticsearch as a service was an interim step in a longer term vision), complexity of the managed service itself, integratability (is that a word?) into other AWS services, maturity of the managed service, and probably a few other things I'm missing.

We've seen our teams go both from managed to non-managed and non-managed to managed with relative success - to give scale, across all of our accounts we spend way north of $3 million/month at AWS so this has happened within our realm a quite few times. The short, unsatisfying answer is that _it depends_. We have an internal policy from the suits that "if there's a managed version, use it" but most of our teams are thankfully smart enough to take that at face value and do their own analysis.