Are any adjustments for ZFS necessary in 8.1 amd64?

[Trever]

Apologies if this has been answered previously, but I can't find definitive info.

The FBSD handbook recommends a customized loader.conf when using ZFS (for all architectures):
vm.kmem_size="330M"
vm.kmem_size_max="330M"
vfs.zfs.arc_max="40M"
vfs.zfs.vdev.cache.size="5M"

Is this still true for the 8.1 amd64 release?  I've read various places that it is not and that handbook is NOT up-to-date.  Out of the box, amd64 8.1 ZFS so far "just works" without any customizations other than to make sure it turns on at reboot.  But systems are fairly quiescent, we have not gone to production yet.

In addition to the handbook recommendations, are there 8.1 amd64 tunings that should be done for a vanilla server?  (Will be imap server, actually.)

Without tuning as per above, I see this on our systems (sysctl -a):
vm.kmem_size: 8318648320
vm.kmem_size_max: 329853485875
vfs.zfs.arc_max: 7244906496
vfs.zfs.vdev.cache.size: 10485760

Our systems have 24 GB of RAM.

Thanks!

Trever