ZFS and dedup

So like most people I just have an array with parity drives. This is fine i don't need the faster reads of a ZFS pool. However, with dedup in ZFS and the new RAID expansion coming I was wondering if/how much dedup would save me from my array, as a lot of it is media there will be a lot of duplicate date you would expect (opennig/closing credits etc).

Has anyone moved from an array to ZFS and seen a reduction in used space or is there a way to calculate the saving potential?