When I saw MA last year there was a pretty big crowd. The point that they don't tour often is a good one though, and I feel SS does still bring out what is left of the deathcore crowd. Still, i don't see MA doing it unless they co-headline, and I think they could easily play last, since the last band is usually always DM (except I guess BDM).
4/25 Full of Hell
6/15 Mutilation Rites