G'day Paul,
I agree that an "Initial Sync" option via USB would be fantastic.
The way we were thinking of getting around it was to temporaily locate the "remote" DSS on the local lan, and just manipulate the IP routes.
While we have not actually done this yet, we couldn't see why it wouldn't work.
Of course we have the advantage of the two DSS being in the same city :-)
I don't now if that is an option for you?
We also have a test rig that has a very similar configuration(same RAID controller NICS etc just different CPU/Mem), so our other thought was to just ship the drives and put them in the test rig, change the routes, replicate, revert the routes and return the disks.