Read the rules carefully. You have to be able to submit your m.s. (in its entirety and with an excerpt) in M.S. Word. Their format is spelled out but sounds pretty standard.
So, it seems to me this is a little like the Pillsbury Bake-off. If you sell something, you want more consumers. Of course, Pillsbury's contest doesn't have "mainstream," "literary" and "genre" distinctions. My works is all genre, but hey, the contest is free! I entered anyway. Now if I can just work crescent rolls into my novel...