The XN5004T deals with encrypted data very well. The write performance is very good at both connection speeds, just dropping 2.2MB/s in RAID 5 and 2.6MB/s in RAID 6 with a 10GbE connection and 7.6MB/s (RAID 6) at 1GbE. It doesn't drop any bandwidth in RAID 5 at the slower connection speed.
Read performance at the faster connection speed isn't as good as the write, with some 15.3MB/s being lost in RAID 5 and 17.5MB/s dropped in RAID 6. At a slower connection rate the dropped read bandwidth is much reduced, just 7MB/s in RAID 6 and 6.3MB/s in RAID 5.