If you will need to resize any xfs FS to a smaller size, you can do it on xfs. For this reason I do not use xfs. Fstrim is show something useful with ext4, like X GB was trimmed . On xfs I see the same value=disk size. Maybe I am wrong, but in my case I can see more RAM usage on xfs compared with xfs (2 VM with the same load/io, services and virtual resurces on 2 identical nodes ).
In my landscape I do not see any advantage from any point of view using xfs. And I use xfs/ext4 exclusive on top of zfs for at least 5 years with many different services (iscsi, gluster, nfs, samba, databases, webservices, mailservers, and many others ...)