Darren,
I assume your FC traffic on the LES circuits is FCIP? If so, then the MDS can mark the IP packets with a specific DSCP value, and if the routing/switching gear in the LES is configured for OoS, and the load is sufficient to invoke QoS, you can prioritize the FC traffic.
With FCIP you can mark control and data traffic with the same, or different DSCP values. You can not distinguish between SRDF and other FC traffic. All FC data traffic is treated the same by the FCIP tunnel with regards to DSCP marking.
I have never seen any recommendations for SRDF/S to require an LLQ.
The recommendation for a FCIP synchronous traffic is to mark the Control traffic with DSCP 48, and Data with DSCP 26. Control traffic is Switch to Switch, and Data is RDF port to RDF port traffic. This should put the FC Control traffic in the same class as Routing protocol frames, and the Data slightly below voice and video, and above Network Management and best effort.
Your specific QoS schema might be different, so you should work with the network engineers managing the LES for specific values to use.
Here is a link to some Cisco information on DSCP marking.
http://www.cisco.com/en/US/tech/tk543/tk757/technologies_tech_note09186a00800949f2.shtml
Hope this helps,
Mike