I think that as it is, Villains are too weak. 4 out of 16 and they don't have a nightkill, let alone know who all of their partners are? Not sure if 6 Villains isn't too much, maybe 5 would be the sweet spot, with a 2/3 distribution to the tribes.
Other than that, I think this game is just too slow-paced to be interestng to me. It is designed specifically to cntinue right until the end, so that's 3 tribe Day plus 8 unified Days, so 11 Days and 11*7=77 real-life days. And if after some point no new information is issued, I think the game could very easily stall.
The idea is neat, but it needs some refinement to attract my attention.
While it's true that they have no night kill, you're still losing 2 players per game phase in the first 3 days - no different pacing than if there was one lynch + one night kill. Granted, they don't control one uncontested, but that's a balancing concern, not so much a pacing one.
In a 9 player, 2 scum game, scum is expected to survive 3 lynches on average to win. Here, that moves them on to the second stage. And because in each individual tribe no nk's exist, there are more candidates 'per day' for scum to get mislynched - so it's not as tight down to the wire.
Further, a 9 player / 2 scum game vanilla isn't considered unbalanced for scum (that is, they aren't seen to have a disadvantage) - here it's 8 player / 2 scum, AND the scum have daychat, so I would be really surprised if they need a natural boost. More mislynch targets per day + daychat should keep it balanced.
Lastly, for game length, that is the maximum it could go. If players are voted out sooner, it goes faster. After the merge, deadlines are cut short for the express purpose of combating a stall.
Yes, there's no new information to be garnered after you're down to 9 - but this isn't strictly a mafia game. That's a large part of the hybrid quality. Whatever faction you may be, you know your side has a better chance of winning with you in the final 2 than any other random person - so you need to convince others that you should be one of two left, while also picking who you trust. Of course, everybody else is doing the same, and previous game phases and interaction and flips influence that decision. It's not just about randomly removing until 2 are left.
And then of course, even if you make it, your fate is decided by those that are removed to get you there. They've got to examine your entire game in context of what they know to determine your likely faction.