Right.. I would not want to run iSCSI over a WAN connection
The NAS would indeed be presented as an iSCSI device to the 2008R2 server on the local site, not the datacenter site.
I also realise by doing that i need to change the repository of the backup job to the repo on that specific server and not use the SMB share anymore.
Dont know if i want to go that route though.. It seems to work fine as it is now..