There is at least one benefit using ZFS: encrypted subvolumes (also
known as datasets).

Currently in Guix it's impossible to have a subvolume for the store and
an encrypted subvolume for /home.
In order to have an unencrypted root and an encrypted /home, we must put
them on different _partitions_ so that we can crypt /home with LUKS.
This has the big downside of imposing a fixed size at creation time.

With ZFS, it would be possible to an encrypted /home without encrypting
/gnu/store and without fixing the size at creation time.

-- 
Pierre Neidhardt
https://ambrevar.xyz/