I would still go with skolas since you don't need all 6 to beat VoG. Someone could just as easily join at the end die and get carried through to get the rewards. At least with skolas they had to stay alive enough to pass the essence and in theory get the mines. Now if there was a way to tell that the person at least was a sword bearer and relic holder at some point that would help but since there isn't I think Skolas is the best judge for now.