An update on this. When you setup replication between arrays you can force it to use a dedicated IP address for replication.  So basically I have created a shared server on each SP with no NFS or CIFs so that I can assign a dedicated IP address to port Eth5 on each SP.  Now iSCSI replication uses those ports which are connected at 100Mb to the IP switch and this is my workaround for throttling the link.  Hope this helps others until EMC add this capability in a future release which I'm sure most SMB with slow links would appreciate.
I have a customer with a link shared with other traffic which needs to throttle the VNXe replication traffic only.   Anyone know how this is acheived? Or is this an enhancement request?
Is there any way to throttle VNXe remote replications