But I still think zfs gets most things right; I see the argument for a concistent system managing caching/logs, volumes, data integrity, discard support, compression, snapshots and encryption.

The fact that it's the first serious, open, cross platform solution (Linux, bsd, Mac, winnt) that provides encryption, integrity and filesystem is a nice bonus.

And the integration of snapshots and fs dumps via zfs send/receive is beautiful.

I think zfs makes sense like one fat layer - networking can go below (drdb, iscsi) or on top (iscsi, nfs, cifs).

Encryption need to be somewhat holistic - for making sane performance and data leaking tradeoffs.

Although, I do prefer the durability of XFS or ext4 (depending on workload) vs UFS, and the setup you described is totally maintainable.