Our original intention in doing this research is to answer the question "how much do we lose in terms of latency and throughput?" So, as you've said, flannel's aws-vpc is equivalent to out of the box k8s/AWS solution, flannel's host-gw is equivalent to calico. Since they use same "backend", in benchmarks we focused on flannel because it's easier to switch in flannel from one configuration to another (basically just put new config via etcdctl and restart the daemons).

However, thanks in pointing it out. In the article we should state our motivation clearer and add references to another solutions, such as calico.