Kevin,
For all versions of the FDK before 11, I use Multi-threaded (/MT). I use VS2008 for all of those, though. I am confident that the /MT switch builds a robust DLL, but I won't say that /MD can't work. I've just never used it. If the DLL compiles without errors and doesn't crash FM when it loads, I'd say you are probably in good shape.
Russ