I am doing tape backup of the dedupe store since I use VDR. I am testing recovery from tape to dedupe and from dedupe to vm on a regular base because I will never trust a disk to disk backup. Worked fine yet.
But I am not using a NAS share as dedupe store, I am using a RDM. You have to shut down VDR to get the dedupe store to tape. Just have look at this thread http://communities.vmware.com/message/1505632#1505632. There two different ways presented, RDM and SMB share.
At least using RDM there is no risk that VDR is hitting the backup to tape process. When VDR tries to start while the dedupe store is mounted anywhere else, VDR won't start.
You will also have some kind of influence to the integritiy check timer. It's just a work around until VMware gives us real control about it, but it works - at least for me. Just have look at this thread http://communities.vmware.com/message/1508463#1508463