Agreed this is something I have toyed around with in my mind for a bit now. Personally I think having characters such as Sammael or a bike mounted Interrorgator Chaplain/Librarian helps to make a force like this all the better. For me I would have as many black knight squads as I could get, a command squad and a dark shroud or two for support. then maybe the Flyer formation for fun or a support squadron to help if I know my opponent is going to charge me. I would only use an attack squad to kill tanks personally 2 attack bikes with MMs and a landspeeder with 2 MM is scary. Alternatively I would give my squads metla bombs.