3 of the same character is a waste in Crota's end though; gear drops like candy. In six runs I'm only missing 3 pieces of gear across all three classes (hunter helm, Titan helm and grieves.)
I understand the temptation of running three of the same class in the Vault, hell it took me some 10 runs just to get my full hunter set; but CE is simply way too easy to get gear from to bother...