It's the old saying: "$10 for the part, $990 for knowing where to put it"
You get a feel for what works and what doesn't, provided you know the relevant facts. Doing a 10RPS system is completely different than 300RPS. And if the payload is 1kB the problems aren't the same as with the one with a 10MB payload.
And if (when) you're using a cloud environment, which one is cheaper, large data or RPS? It's not always intuitive. We just had our AWS reps do a Tim "The Toolman" Taylor "HUUH?!" when we explained that the way our software works is 95% cheaper to run using S3 as the storage rather than DynamoDB :D
