I currently have a 50 MM that is Thugs/Dark. I've been thinking of actually doing Dark again due the great defense I can get from the set. My MM as it stands has his S/L defense capped. He really feels like a tank. The only problem I have witth Thugs (and I'm sure a lot of people do as well) is the damn Arsonist's burn that forces mobs to just scatter all over the place. I'm really hoping with Demons I can eliminate the running around like a chicken with my head cut off.
Also who doesn't love a pet who heals for you