I have seen that done successfully several times. On our Elite series units, the is especially easy to set up. You just set up the remote machine to contact the target machine. Port forwarding remains the same as for remote client connection. (you don't have to set ports for each camera, just the DVR/NVR itself)
Then to add the cameras, you pick 'Private' protocol and there is a channel select drop down - enter the remote DVR IP and select which channel you want from it.
The only limiting factor is upstream bandwidth at the central location. You will be sending all cameras at full resolution out the door to the remote recorder. An upstream rate of 1 or 2Mb isn't going to cut it for that amount of data.
But in the long run, considering storage fees for FTP or Box or similar - it should work out in your favor to go with the remote NVR.
That's my two cents woth...