PC-BSD comes with the Life Preserver which is just a GUI around
rsync. They swear by it. However since you are using ZFS you might learn how to take
zfs snapshots. I would recommend reading following Michael Lucas articles for the survey of zfs snapshot tools
http://blather.michaelwlucas.com/archives/2128
http://blather.michaelwlucas.com/archives/2140
For the record for file systems other than ZFS I personally use
rsnapshot and for off site/cloud backup
duplicity (comes with the useful front-end script
duply). No GUI however.