After I select a device in the MPMC GUI, I find that the DQS and DM values do not reflect the actual values.
The correct values are calculated by the MPMC Tcl script which is run after you make the selection. The correct values are not updated in the GUI.
This problem has been fixed in the latest 10.1 Service Pack available at:
http://www.xilinx.com/support/download/index.htm
The first service pack containing the fix is 10.1 Service Pack 2.