/boot/loader.conf or /etc/sysctl.conf ? zfs tunables

[John]

Hello list,

Is it safe for all zfs tunables to go in loader.conf? I see some are
recommended to go in sysctl.conf. Well, not recommended, but quoted.
Using /boot/loader.conf would, to me at least, be more systematic. Is
there any harm in defining them all in there? If it is, it's not always
obvious which goes where.

thanks
-- 
John