We just had an 11 player game with both a reaper and a possessor. This was a cult game that also included an evil king.
Overall, there were only 5 Blue Dragon players. The evils+neutrals actually outnumbered them for the beginning.
For the sake of balance, fair play, and fun, I strongly suggest that the game only add multiple NKs into the role pool in games with 14-16 players.
I know balance changes aren’t until later, but the CURRENT state of the game being in Alpha with low activity, means that the potential for this occurrence is much higher NOW than it will be in beta and in release.