Anyone have any experience with GNBD?

What kind of performance and security differences are there in running GNBD vs NFS?

We’re planning an implementation with an external storage array (DAS) and want to use a shared filesystem.  We have 10 or so clients that will be connecting to the shared filesystem.  We have duplicate systems and arrays and were planning on using keepalived for failover of the NFS, however we are looking into using Cluster Suite, GFS, and GNBD to do the same thing.  Would it just be overcomplicating things and not really providing any clear benefits?