Converting a non-HAST ZFS pool to a HAST pool

[Zaphod Beeblebrox]

I'm wondering if I'm missing something here --- because I'm wondering
if running HAST under ZFS isn't a step backwards.

My quick read of HAST seems to indicate that it's going to manage two
disks and present them as one disk to ZFS.  The design problem with
this (especially since we're talking a _lot_ of network (and memory)
transfers involved) is data corruption --- the idea that ZFS protects
data better when it can determine one disk has it right while another
disk has it wrong (as it can when it manages the two disks).

Wouldn't it be better to just have network (iscsi-like) spools
attached to ZFS?  Individual spools could still fail.  What am I
missing?  Is there a better description of HAST than the FreeBSD wiki
page?