Can you explain the draw of Async I/O? A single request will not be faster, but you may get more concurrent requests going due to running some while some are waiting for I/O to finish? Is that correct?
What an Async I/O model can do is allow the amount of resources consumed by parallel execution contexts to be reduced - therefore allowing you to service more concurrent requests in parallel. But not necessarily any faster, if I/O is your bottleneck in the first place.
It can also be used to give more predictable performance under loads with i.e. response times, if the responses are not dependent on I/O operations to complete.