For instance, I've been mucking around with building fox-gate lately. Well, as I'm doing many modifications to the system in order to try to get this build to work, I decided to do the following:
$ pfexec zfs snapshot rpool/ROOT/preview2@prefox
This made it easy to clone that snapshot, do my updates (including a BFU, which I was pretty sure would end poorly), and be assured that in the worst case scenario, I could always boot that snapshot to figure out what I broke on my original, or even just revert the original entirely. Luckily, I figured out a workaround for my booting problems after the BFU, so I didn't have to revert to the snapshot, but it is definitely very empowering to know that the option is there. No having to deal with backups or a convoluted restore procedure. Just zfs snapshot, zfs clone and zfs rollback.