Btrfs/ZFS Network Replication

Is it possible to replicate a ZFS or Btrfs raid volume in real-time (or as close to as possible, network specs aside) over a network? ZFS and Btrfs are ideal because of their CoW properties. I'm thinking something similar to DRBD, but DRBD won't work because it requires a single-block device, and we're ruling out the option of exporting each disk as a DRBD device because that would get messy. I don't want to use send/receive because they would be too slow, even if scripted. Ideally, I'd like something relatively simple to avoid unnecessary complexity.