I still can't reconcile zfs in the installer. There's no warnings or information upfront about how you will make your filesystem into a nice brick if you upgrade your linux kernel and forget that your filesystem has to be manually upgraded with that kernel version. Distros should not include filesystems that aren't in the kernel in their official installer. Fedora made the right decisions with btrfs. If users want zf…
If you use DKMS, then you might have issues, but there's no need with Ubuntu (and other distros like Manjaro) anyway.
Btrfs is probably never the right decision - use the FS that's right for you and your workload.