Living in Gallia county i am "lucky" enough to know a few Marshall fans as well.  I would say by a 2-1 margin they would prefer to be in MAC.  The biggest reason they give was mention previously and it has to do with being able to make road trips to follow the team.  A couple even stated the rise of Boise State shows that a team from a MAC type conference can make a splash on the national stage.  Don't get me wrong, I hate Marshall with every ounce of my body (yes more than Miami), but I really enjoyed them being in the conference.  I know it always fired up all the OU fans in Gallia, Lawrence, Jackson, Scioto and Meigs counties since we side between the two.