Oracle's ZFS encryption is susceptible to watermarking attacks: http://lists.freebsd.org/pipermail/freebsd-hackers/2013-Sept...

The "more advanced" claim is certainly disputable but OpenZFS has a larger and rapidly growing user base. The ZFSonLinux and OpenZFSonOSX ports in particular are bringing loads of new users to the table, and that means more testing, more contributors, and in the long run more features. (I've also become an occasional ZoL contributor that way.)