As you all probably know,
zfs is going to be usable, albeit in a beta-form but i guess they will make good progress over the coming months. I'm already using zfs as my "warehouse" filesystem and want add several discs to it in the months to come and as soon as usable will add my home-directory to it, leaving only the system- application- and bootable Systemfiles to HFS.
So, is the underlying filesystem unrelevant for SD-Backups (i'm NOT talking about bootable backups here, because zfs isn't bootable at this time) or do you need to make adjustments for using zfs as the filesystem of choice for people? For the time beeing i trust SD more than ZFS
so this will be very important for my strategic planning.
As far as it goes, leopard comes with read-only zfs-support, but maybe on of the following 10.5.x updates will bring us zfs-writable-support. Maybe this get's postponed to 10.6, but the zfs-team at APPLE wants them to go out as soon as possible...