Including your 9x write amplification in the number of "consistent writes" doesn't count -- like at all. I'm amazed nobody called you out on this yet. You're doing 3k batches per second with 4 logical writes each, right? So that is at most 3-12k writes per second using the way that every other distributed database benchmark and paper counts. Or otherwise - if you continue counting writes in this special/misleading wa…
Even if we focus on 120k writes and ignore the low transaction number then it's still an average result. They use c3.4xlarge to run 5 shards each with 3 replication factor. It's 1500 writes per core (120k / (5*16)). Etcd easily does 5227 writes (I believe it can do even more) on "Standard DS12 v2" so it's 1306 per core which is very similar.