If the LUNs have backend activity, they should trigger FAST movements.  Chances are the active parts of these LUNs would all fit in EFD, so it should show that we can move active stuff to EFD.  You may also see demotion to SATA if they bind to the FC tier.  Seems like a reasonable demo to me, however without the full capacity and workload, it will probably be more optimistic than when everything is on the VMAX.
Hello,  I have a client who is migrating from a DMX to a VMAX, and would like to see FAST in action. The plan is to migrate 10 hosts (which have say 5 LUNs each on the DMX) to the VMAX - but migrate only 1 LUN for each host. The remaining 4 LUNs for each host would remain on the DMX.   The intent is to see if having a total of 10 LUNs beloning to 10 different servers on the VMAX would trigger FAST to perform any relocation, and see the reports and relocation process, etc.   Is this a good way to test FAST? If not, what would be the best way to demonstrate FAST to the client with the current architecture?    Thanks Prasad. 
Test/demo FAST