A NAS setup can be tricky to get the security right (as well as in theory being a slower protocol) and you can't use Deduplication against NAS (Share Level) access either
Accessing a remote site over SAN prototcols might not be that valid either
You might want to look at 2 Backup Exec servers (one at each location) in a CASO/MBE setup both with Deduplication folders (on SAN or Directly attached disk arrays)
You then backup to deduplication on the main site and use an Optimized Duplication strategy to copy the required backup sets up to the deduplication storage foleder managed by the BE server at the remote site.
One final point you probably should not use Deduplication Storage (or fixed disk storage) as the only storage type when thinking about long term retention of your backup sets - so you might potentially still need tapes (or detachable disks) for long term critical backup sets. As one example of why - Crypto locker viruses can effect disk storage and once in a given environment might affect all your disk storage across multiple servers. Storage that is not permanently online is less susceptable to such things. (this is of course malicious corruption of disk data, however you could have other causes of corruption, over time, that could have the same effect )
