This must have been downvoted by people who don't understand HPC, as usual here. While, typically, latency is the most important metric for an HPC fabric, it's

This must have been downvoted by people who don't understand HPC, as usual here. While, typically, latency is the most important metric for an HPC fabric, it's not the only one that may be more important than bandwidth (message rate, contention, offloading...). It's also important to have detailed monitoring, which I guess you won't get from any such provider. Being told, even of the old networking, that it's all terribly clever and we shouldn't ask questions isn't a good way sales pitch.