Yeah I ended up going with mirrored vdevs for the ability to expand to 6TB drives later... then I was told (in IRC) that a single bit-flip would cause a complete pool failure.
Uhh if they're mirrored, a bit flip is not only detected by ZFS but also corrected, whether it happens passively during a normal file read, or scrubbing, or presumably a resilver.
Even with ZFS as I understand it, you should just set up your storage pool then mirror it and be done....boom 50%