I've played only a couple of games with mr.Fluffy (Rogue Necro) and It didn't last more than a couple of turns, however the pack upgrade is very nice, gives the res some mobility helping you get your pieces in the right place, it will attract a lot of firepower for sure, if you manage to get it in melee he is quite scary though.
I think it benefits a lot from close deployment zones such as close deployment or Flank, its Terrifiyng (all) 13 can give some problems to some crew (except Rasputina of course).
Overall is one of my favourite pieces to play with Molly, i'll try it with McMourning as well, but i must agree with everybody and say that at the same point cost the valedictorian is a better choice