Got another hard drive, a little over 8TB now. Decided to move some data about.
One of the drives on my zfs array faulted while I was copying a few hundred gigs of stuff. Nearly had a heart attack when I noticed. I ejected the volume and reimported it. The console came up and told me it was reslivering. I came back a few hours later and it was done. Which means it not only fixed the label mismatch but then rebuilt only the data that had been changed. Color me a believer.
In other news, apple dropped zfs from the snow leopard features pages. People have been getting worried about the project being cancelled. The more probable explanation is that apple split off their leopard zfs efforts earlier this year to work primarily with the snow leopard branch. Since then, they have not released any new 10.5 bits. Meanwhile, the decision was made not to include zfs in the snow leopard release as officially supported. So, the maintainers are sitting on the new bits till snow leopard comes out.
That would be my hope. I have been wrong many, many times before.