Hello,
For you scenario, I would send the Data deduplicated over the WAN link.
How to proceed ?
Put a StoreOnce Software system at each site (no need to be CS but it can be a standby CS on the other site).
Configure at each site a B2D device
Add each systems from each site as a server-side gateway to the other side
ex: Site A B2D device = 2 Gw (one from site A used for backups + One from site B used to copy the datas)
Configure your object copy to read data with the local gateway and send the data to the local (server-side) gateway for the other site B2D device.
Please note that to perform that the DR site Cell Manager should be a standby one (I mean no CS service running and a simple client of the production Cell)
Depending of how to you transfer your IDB on your DR site, you'll be able to promote your standby Cell as the "real cell"