How can I see improvement in performance with bonding?

The increase in performance using bonding will not be apparent in your system until you increase the I/O load on your network.  If you are only transferring a relatively small number of files that are small in size, say, a few hundred MB, you're not going to notice any difference.  To see the effect of bonding, you need to significantly increase the load on your system, transferring large numbers of files which are larger in size.   You will also see a difference by adding many servers and/or workstations transferring data on the network.