Can anyone give an example in which there would be less network bandwidth? This tree topology seems like it would use more bandwidth.
By having a proxy/repeater/site server, you are reducing the amount of WAN traffic you need to send.
low cost end replicas at the end. if the bandwidth usage is half the cost in their multihop topology, 14XXXX compared to 16XXXX? depends on the number of proxies or replication and pricing.