Client compression would be very helpful...
How big are the boxes ? ? ?
and a full restore would take time but the data would be there.
I've backed up NT boxes from Atlanta GA into Tulsa OK  (I'm pretty sure the
nodes are still registered...)
they run fine but my network speeds are a little better than what you've
mentioned.
Ya know... it wouldn't hurt to toss on the client and do an initial test and
see.
Worst case, you delete its data from the server and delete the client.
Always a bottle neck somewhere :-(

Dwight