Corrupt GPT on ZFS full-disks that shouldn't be using GPT

[Quartz]

> Remember, ZFS
> leaves space unused at the end of a disk to allow for variations in
> nominal disk size.

Holy what the heck, no it doesn't! One big issue with zfs is that you 
CANNOT shrink a pool's size once it's been created, for any reason. You 
can't remove vdevs, and any replacement disk must bigger or exactly 
equal in size; even a disk with one less sector and you're SOL. This is 
my biggest gripe with zfs by far and in fact I just asked freebsd-fs 
about this less than a week ago wondering if it had been addressed 
finally (it hasn't).