I'm wondering about the rationale for using ElastiCache/SimpleQueue vs just having "Cache" and "Queue" tables inside of DynamoDB respectively.
It seems that the network latency to the Cache/Queue services would trump a lot of the performance gains, and that having EC2 treat Dynamo as it's cache/queue service would offer the same latency and throughput (since Dynamo allows a fixed low latency under any load).
Is it mainly about the price of dynamo vs other services under load?
Does anyone have any rough latency numbers comparing Dynamo with ElastiCache/SQS?
Are there other more important considerations that I'm missing which justify the additional complexity?