Yes, the layered approach will always consume more bandwidth unless you just happen to hit the case where your transaction is read-only and the layer process is

Yes, the layered approach will always consume more bandwidth unless you just happen to hit the case where your transaction is read-only and the layer process is colocated with the storage server where your data is. The upsides far outweigh this downside in my opinion. The fact that writes are buffered locally before committing the transaction (improving latency) is probably enough by itself to overcome that downside.