Smarter filetransfers than rsync?

Rsync will not use deltas but will transmit the full file in its entirety if it - as a single process - is responsible for the source and destination files. It can transmit deltas when there is a separate client and server process running on the source and destination machines.

The reason that rsync will not send deltas when it is the only process is that in order to determine whether it needs to send a delta it needs to read the source and destination files. By the time it's done that it might as well have just copied the file directly.

If you are using a command of this form you have only one rsync process:

rsync /path/to/local/file /network/path/to/remote/file

If you are using a command of this form you have two rsync processes (one on the local host and one on the remote) and deltas can be used:

rsync /path/to/local/file remote_host:/path/to/remote/file

From the DESCRIPTION section of man rsync:

Rsync is a fast and extraordinarily versatile file copying tool. It can copy locally, to/from another host over any remote shell, or to/from a remote rsync daemon. It offers a large number of options that control every aspect of its behavior and permit very flexible specification of the set of files to be copied. It is famous for its delta-transfer algorithm, which reduces the amount of data sent over the network by sending only the differences between the source files and the existing files in the destination.

So that would be a "no".