I used to box successfully with 4x RKs and 1 Champ (as tank). This was post MoM, but pre any other expansions. I could do Carn Dum solo pretty easily with this setup, farming for the trinkets I wanted. I imagine throwing a support class in there would be handy. The thing I liked about the Champ was the easy AE aggro w/ the tank-mode and ae skills. Better/easier than the Guardian reactives in boxing, imo.