I recently did an arch with zfs root setup. You have to make a custom install ISO that has the zfs module to do it. After it's installed the main annoyance is the zfs module only works with certain kernel versions and often arch has updated the kernel to a version not supported. There's a repo with pinned kernel versions or you can just use the lts kernel.

FreeBSD is much easier but I needed better Linux compatibility for this machine

We run ZFS for a system at work on linux. Yea, it isn't as seamless and nice on FreeBSD. Only reason we aren't running FreeBSD is the application that needs to access that storage is .NET, and no .NET support for FreeBSD.