From the FAQ:
"When is Datomic not a good fit?
Datomic is not a good fit if you need unlimited write scalability, or have data with a high update churn rate (e.g. counters). And, at present, Datomic does not have support for BLOBs."
I agree Datomic is far more than a write log but in the context of this thread, the discussion was about write logs.
Also, how are you defining "high write volume"? Have you looked at metrics of how fast Datomic's serial transactor can be?