We've found it easier to load large datasets using CloudHarmony but have run both.
I'd recommend reading through http://d0.awsstatic.com/product-marketing/Aurora/RDS_Aurora_.... It is oriented towards SysBench, but will help you set up your clients to have enough network throughput to run a full test.
Generally, we find the performance comparison improves on large instances, high throughput workloads, or when the data set does not fit in RAM.