I did try just using two folders on volume_1 and set the DNS325 up to transfer between the two folders, the file dates were kept intact. I currently can't try volume to volume backups until I know everything is working and I can retire my DNS323.
I was unable to get the following to work; if I deleted a file in the one folder, it did not delete it out of the other folder. Would be nice to add a true sync option so you could decide if you wanted any files deleted on volume 1 would also be deleted on volume 2.